utomotive Wiring Tips - Using Relays

Things To Consider When Wiring Accessories...When wiring anything in your vehicle that draws heavy current such as high powered offroad lights or audio amplifiers, there are a few things to consider. Number one, make sure you use wire that is rated for the amperage that the accessories is going to pull. It is always better to have wire that is OVER rated rather than wire that is not rated high enough. If wire is used that is not rated to handle the current that your accessory will pull, the result could be overheated wires that could melt the insulation or the electrical plugs found throughout your vehicle (see image below), causing a short or worse yet it could result in a fire. If you know how much current your accessory will draw you can determine what gauge wire is appropriate for your application.

Personally I like to use wire that far exceeds the current draw of my accessory. It's overkill but in a few applications I've used heavy gauge stranded industrial wire with water and chemical resistant insulation. That way there is no question as to whether the wire is rated high enough or not. If this approach is taken, it is very wise to place a fuse at the battery end as close to the battery as possible. Most wire in a vehicle, if shorted out, will burn up before the battery overheats and possibly explodes. If wire that is over-rated for vehicle use is used and a short occurs, a short will most likely result in damage to the vehicle of some sort unless a fuse is put in line as close to the battery as possible. With the fuse there, in the case of a dead short, the fuse will burn out first before any damage could occur.

Above, a melted electrical connector that had been overloaded.

T-Tap connector

Where to Get your PowerThe second important thing to consider when adding accessories is to determine where you will get your power. Many people will consider tapping into the hot wire of an existing circuit using something called a T-tap or quick slide connector, which are designed specifically fortapping into an existing wire. This is not always a good idea for several reasons. First and foremost, tapping into an existing circuit puts additional load on that circuit. The additional load placed on a circuit or wire may exceed the limits of those wires, connectors and fuse. Overloading a circuit will do one of two things. First, it may blow a fuse. So people will sometimes place a larger fuse in the fuse block to handle the extra load on that circuit. BAD IDEA! The fuse may hold but the resulting extra current may be more that the wire is rated for creating heat that can melt wires and connectors and start fires! The connector to the right was overloaded and fused two adjacent terminals together, causing a short the blew the vehicles main fuse. Before the fuse blew the connector actually started to burn. The wire that carried the extra load also had melted its insulation and in places was exposed. Luckily for the owner of this vehicle, it did not result in a fire but in many cases it does.A better idea....With accessories that pull a lot of power it is always better to get your power directly from the batteries positive terminal rather than tapping into the existing fuse block or wiring harness. In most cases the vehicles existing fuse blocks, wires and connectors are not rated to handle the additional load of high powered accessories such as offroad lights and amplifiers. If you are the kind of person that likes to add all kind of goodies to your vehicle it might be worth installing an additional fuse block that handles non-critical items like offroad lights, CB radios, power inverters, audio equipment, etc. This additional block can then be powered by a heavy duty wire capable of carrying the current required of all the accessories on the block. Be sure to fuse the block at the battery.

Another important thing to consider is how you control the switching on/off of the power to your accessories.In almost every case where high current is required, the switch you will use to turn on the power should not handle the load because most switches are not designed to handle higher amps. The job of switching the power is better left to a relay. What is a relay? A relay is a device that, through a magnetic induction coil, turns on the power for you. The switch that is installed in the cab of your 4x4 actually only powers the relay itself which draws very little current. In most installations a 30 AMP relay from Radio Shack (Auto Relay Cat. Number 275-226) will do unless your amperage demands exceed 30 amps. I like to used a lighted switch in the cab to let me know if driving lights are on.

Offroad Lights or Accessory Wiring Diagram using a 4 - Pole Relay Relay

Click to Enlarge

The method I use for wiring the lights and other external accessories, for the most part, follows the diagram pictured above. As in the diagram a wire is run from a 12 volt power source to the switch in the cab and out to the relay placing a fuse at the source of the power. (Follow the relay's wiring schematic when connecting the wires to the relay) One of the relays terminals goes to ground. Then run a heavy gauge wire from the battery to the relay placing a 30 Amp fuse in line very close to the battery. Do not connect the power to the battery until all wiring is done. Then I run a single heavy gauge wire out to the lights or other accessory. If installing lights, split it into two leads at the lights. If you do this be sure the wire is rated to handle BOTH lights since it will carry the current of both. The diagram shows two leads coming from the relay. Then I run the second wire of the lights or other accessory to a good ground on the frame of the vehicle. If the wires will not be soldered together and crimped connectors will be used it's a good idea to put a dielectric paste on the connectors where they come in contact. This will prevent corrosion as time passes ensuring a good connection. Then double-checked all wiring before plugging in the power.

Electrical: Circuits, Wiring, Relays, SwitchesFAQ Home

Volvo Maintenance FAQ for 7xx/9xx/90 Cars Version 5.0Electrical Diagnosis TipsFuse LocationsRelay LocationsHot Fuel Pump RelayRelay and Fuse Panel RemovalRelay/Fuse Panel Base ReplacementRelay Repair vs. ReplacementPower Window SwitchesPower Door Lock FailureBaked Engine WiringMaintaining Chassis GroundsDielectric vs. Conductive Grease to Protect Connectors and GroundsCircuit Board and Contact RepairPower Windows Operate in OFFRelays Run HotSlow Battery DischargeMultiple Electrical Failure: Ignition Switch BadCruise Control Surges: Worn Servo

Electrical Diagnosis Tips. For a superb introduction to basic automobile electrical diagnosis using a digital multimeter and accessories, see Fluke Corporations website reference athttp://www.fluke.com/application_notes/automotive/beatbook.asp?AGID=1&SID=103Wiring Fault Diagnostic Tips. [Tips from Import Car Magazine]DIAGNOSTIC THOUGHTSWiring failures occur as open, shorted or short-to-ground (grounded) circuits. An open circuit, obviously, is a broken or disconnected wire. Shorted circuits occur when the insulation between two wires fails. Grounded circuits occur when a bare wire is allowed to touch the vehicles powertrain, sheet metal or frame. As for narrowing diagnostic probabilities, lets remember that:1. Before wasting hours of expensive diagnostic time, test all fuse circuits with a DVOM or approved test light. Remember that fuses can fail without showing signs of an obvious burn-through. Since a loose or corroded fuse connector may also cause many intermittent circuit failures, thoroughly inspect and clean the fuse circuits before proceeding with your diagnosis.2. Most wiring failures occur at either end of the wire as a bad connection. Although splice failures inside the wiring harness are rare, some nameplates are notorious for splice failures. Technical service bulletins (TSBs) and Internet sources offer valuable insight to typical nameplate problems.3. Corroded harness connections cause most intermittent circuit failures. Simply unplugging the connector and applying an electrically compatible corrosion inhibitor will repair most connector failures.4. When diagnosing intermittent failures, remember that suspect turn signal flashers, fuses, bulbs and relays can be replaced more cheaply than they can be diagnosed. When diagnosing an intermittent lighting failure, for example, I always begin by cleaning the bulb sockets and installing new bulbs. How much diagnostic time are you willing to spend testing a $0.98 light bulb thats nearing the end of its practical service life?5. Engine, computer and body ground connections should be checked first, especially if the vehicle has recently visited the collision repair shop.6. Keep in mind that most electrical systems, when left untouched, perform very reliably. When they do fail, the failure will be predictable, such as a bad current or ground connection, blown fuse and the like. Most predictable failures can be solved within a two-hour time block.7. On the other hand, the DIY mechanic "short-testing" a cooling fan switch or fuel pump relay can create a multiple failure with unpredictable consequences like burning a wire within a wiring harness. Obvious tampering should always create a red flag... Electrical "red flags" may include newly installed sound systems, electrical accessories, trailer brakes, auxiliary lighting and the like...8. Many circuits serve more than one accessory or function. Years ago, for example, I found that a burned brake light fuse was caused by a loose courtesy light in the ashtray. Without a good magnetic short detector, the problem would have been difficult to solve since a relationship between a brake light and ashtray light isnt immediately logical or clear, to say the least. In other unlikely cases, Ive found an instrument cluster fuse that also supplies field current to the alternator. The moral is, never rule out the effect of one circuit upon another...10. In fact, avoid using test lights altogether. When testing fuses, for example, I use an LED-type test light (available from a major tool manufacturer) that indicates open or grounded fuse circuits and voltage availability. This eliminates guesswork and protects ground-sensitive electronic circuits like air bag sensors.11. Use a professional DVOM with a min/max voltage feature and alarm to test intermittent failures. The min/max feature will record the highest voltage reached in the circuit and sound an alarm each time a higher voltage is reached. For the technician working alone, this feature is a real time saver, especially when performing a "wiggle" test on an intermittent wiring problem. In the same sense, lab scopes are particularly useful to find loose ground connections. During a wiggle or vibration test, loose ground connections will show up as a voltage spike in an otherwise zero-volt lab scope waveform.12. Remember how hard it is to find the trim screw driven through a wiring harness hidden underneath a headliner? A good short detector will help you quickly locate concealed short-to-ground circuits. For about 30 bucks, its a great time saver for you and your customer alike.

Fuse Locations. See the follwoing diagrams for fuse locations in 740/940 and some 760/all 960 cars: 740/940 Fuse Locations 960 Fuse Locations

Relay Locations. See Michael Ponte's excellent illustrations below to identify relays in 740/940 cars. To access relays, remove the snap-on cover over the cigarette lighter, then remove the two screws securing the storage box. Remove the box and you will see the relay tray behind the fuses.

In 960 cars, the relays are in the same location but mounted on a vertical relay board.Relay Identification in UK 760 Model. [Query] I need the relay identification on the relays which are located on the side of the transmission tunnel under the plastic panel in the passenger footwell compartment. These relays are labeled A,B,C,D,E,etc. No disrespect ,but please do not refer to the ones in the compartment behind the ashtray because I do not have that model. [Response: Steve] In my 1990 760gle United Kingdom model the relays are A: main lighting(part); B: motronic/jetronic relay; C: central locking relay; D: foglamp relay; E: main lighting relay(part); F: bulb failure warning relay (front); G: overdrive relay; J: power boost relay; K: rear wiper delay relay; L:windscreenwiper delay relay; M: seat belt warning relay. A, B, F, J, L, and M are permanently attached to the board.

Hot Fuel Pump Relay. The relay should not get hot even if the pump is drawing too much current...until the excess current starts to kill the contacts. Either way, a hot relay is a bad relay. There are three possible reasons for a hot relay:cold solder jointbad crimp jointbad relay contactsAll mean that a point in the relay has resistance and when current flows through that point there will be a voltage drop which means work is being done and that work manifests itself as heat (P = E * I). Over time the bad joint gets worse due to the heat and maybe heat cool cycles, the resistance goes up, the joint gets hotter, the voltage at the pump goes down so it needs more current to do the same work so the joint gets hotter, it gets worse, well you get the picture. At its worst this kind of scenario can destroy a motor because the low voltage condition causes a high current draw which over heats the motor. The relay may or may not be fixable. I usually try to fix them and are often successful. Note that Volvo released an improved relay, which has silver terminals, to solve this problem. If the car's existing relay has copper-colored terminals, replace it with the newer relay.

Relay and Fuse Panel Removal. It is possible to pull the whole relay panel out the front of its opening. Remove the plastic box (which also contains the accessory socket) above it to facilitate this. There is an obvious clip that you bend slightly to release the tray. Lift upward slightly, then the tray slides rearward and out. The opening in the console is just the right size--the tray does not need to be turned or twisted.The wire umbilical attached to it is long enough to allow the panel to be pulled out quite far. This is also how you can hook up accessories to the fuse and relay connections under the panel. Use a good light so you can see well.

Relay/Fuse Panel Base Replacement. My headlight relay got into a bad habit of getting real hot. I had the same problem and after replacing the relay, I replaced the plastic base. It's quite easy, get yourself a 1307160 ($2.89 CAD) and pull your relay/fuse tray out of there. After removing the relay, flip the tray and remove each wire (tape the lug & mark the position). You can usually coerce the crimp-on connectors out by bending the little tab internal to each connector (with a small screwdriver). Once the relay base is clear of wires, unclip and push it out. Install your new base and re-install each wire in the proper position. I find that, using a knife, you can "restore" the little tab on each crimp connector so that it "clicks-in" when you re-install the connector in the base. It is vital to have firm connectors or else they slide out when you push-in your relay! One additional note... The base melts because there is resistance & arcing between the crimp-on connector and the relay lug. There is quite a bit of current going through there and you want to make sure that you have tight connections. You can do that by "squeezing the gulls" of each crimp-on connector. Contacts #30, 87 & 87b are the culprits (not sure if they are all used though). My relay/fuse panel is all plastic. Double-check the part number of the relay base by removing a relay and reading the part number in the center of a "good" relay base.

Relay Repair vs. Replacement. Here's a generic statement about your relay (which I know nothing about) -- this statement displays my bias about the (poor) quality of Bosch wave soldering. If you can pop the cover off the relay, try resoldering all the connections on the circuit board before you replace it. (After all, you have nothing to lose but a few minutes.) The heavy connections that go to large components like the actual relay may need a large soldering iron or gun, whereas the connections at smaller components, such as transistors, should be reflowed using a smaller iron, like a 25-Watt iron. If you're not comfortable soldering, find a friend who is.[Don Foster:] Over time (like 10 years), the solder used in production manufacturing tends to become crystallized and cracks. The type of solder used in high-volume production is different than that used in an electronics repair shop. The problem with the relays is tiny, almost invisible microscopic cracks in the solder. These cracks usually encircle one (or several) heavy connections, such as from the relay or a main lug connector. Under a bright light, and using a magnifying glass, inspect the soldered connections. Simply resoldering these circuit board very often restores them to perfect performance, and it's a whole lot better (and cheaper) than a $50-$100 replacement part. I have recovered literally dozens of Bosch relays (OD, fuel pump, wipers) to perfect performance this way at $0. In fact, I resoldered ALL the relays in my family's 6 Volvos before a failure stranded us.

Power Window Switches. [Switches don't work] I can suggest one course of action that helped to alleviate the situation, take apart the individual window switches and clean them out. The switch pivot has a bit of oil or grease on it and some of it gets on the ball bearing contacts, causing dirt to get stuck and faulty contact points. The same may be true with your child safety locks for the rear windows. It worked for mine, but I think I need to clean the switch once more as it only operates correctly 80-90% of the time going down, and all the time going up. I was even thinking of replacing the switch itself if that didn't work. No experience on the power relays, though.[Symptom: Window does not raise or lower.] [Diagnosis:] Switch. These are fun to fix. Pull the switch assemblies out of the door handle (two metal springs at front and back hold them in: use a screwdriver to lever them out. Then pop the switch out (I usually wind up doing them all as long as I'm there) and pry the side off the little nipples so the cover comes off each switch. Be careful since there is a spring in the rocker, you don't want to lose it. Take out the little metal "lever" and use some very fine sandpaper to neaten up the contacts on the lever and the contact points inside the switch. [Tip from John Yuristy] . I wouldn`t use sandpaper or steel wool on contacts, some are just plated and you will remove the good stuff.[Response:Steve Ringlee] For a detailed analysis of the window switches, take a look at Michael Ponte's analysis athttp://www.mikeponte.com/volvo/pwin.htm. Another solution is disassembling the switches (be careful in removing them from the black plastic holders), de-oxidizing and cleaning them using an electronic de-oxidizer such as DeOxIt from Caig Labs, then using a fine Scotchguard nylon scrubber to burnish the contacts, and finally reassembling them using Caig ProGold protective coating (very small quantities precisely applied) on the contacts to prevent further dirt and oxidization from ruining the contacts. Caveat: I have tried the "rebuild" approach on these switches and found that it did not last that long; I ended up buying a new driver's door switch from RPR for around $30 just to save more work.

Power Door Lock Failure. [Query:] There has been a failure of the door locks on my 740 wagon. The tailgate unlocks with the drivers door but no other function works. Do I need a new lock actuator or is there something else to check? [Response:] There is a switch in the driver's door that sends a signal to a relay mounted on the central relay panel. The relay then sends power to all the lock motors (all doors except driver's door). If some of the locks are operating and others are not, then you have either a wiring problem or a ground connection problem. Either way, the place to start is to remove the door panels on those doors that are not working. Unplug the lock motors and check to make sure they operate freely. If so, proceed to check the wiring with a multimeter - look for bad ground connections, no power on lock/unlock leads when door switch operated, etc. I expect that the three passenger doors are on one harness and that the tailgate has a separate harness lead that comes from the relay. So look for those points which are common to the three passenger doors.

Baked Engine Wiring. [Early-80s to 1987 240 and 7xx cars:] Harness failure often causes multiple symptoms such as rough idling, stalling, hesitation, overall erratic performance and random misfiring. The symptoms may mimic ignition or fuel injection trouble you've encountered on other cars. I cannot address 240 vehicles newer than 87, the friends I help do not own anything newer. In all the 240's I've seen there are several wires that are "flaky": oil pressure; alternator wires and alternator dash signal; knock sensor; water temp gauge; starter from ignition; starter to coil; primary ignition wiring near the ignition coil; and on 7xx cars, harness connectors in the right rear corner of the engine compartment below the ignition coil. ALL the wires from the ECU do not show any signs of deterioration in any of the harnesses we have opened up. Since the flaky set are wrapped into the main harness to replace them means replace everything. At big $$$ for Volvo & the service center. After getting nailed for the 85's harness, I took preventive measures on my 83 and others until we find a long down time to correct the problem. We replaced the alternator and the oil pressure sending wires rerouting them around the right side of the engine bay. We believe that if the alternator wire shorts to some other wire that is where the big problems could occur. The alternator wire has the potential to supply a constant 12+ volts to any of the others ( which are to ground) and act as a heater wire inside the harness, getting hot enough to melt all the others. In my 85 it was from the starter wire to the alternator wire up by the dash connector and was caught before much damage was done. Had it replaced by the dealer thinking insurance only to find that insurance refuses to cover this problems in Volvo's. Cutting open that harness revealed NO damage or deterioration to any other wires in the harness except the above wires. Our solution: We reroute with new wires to all of the above sensors. Best done with some other time consuming task. To make it really easy we release the intake manifold. Takes two of us about 3 hours to reroute all wires and replace the manifold. Tried it first without releasing the manifold and it took 8 hours. I believe Volvo could have created a replacement harness consisting of just these wires but did not do so because of $$. Another is that if you catch the problem soon enough no other wires will fry because of a short between two of the bad wires. Wait too long and other wires will be damaged from the heat of the short. Since this is probably about the time Volvo found out about the problem, it looked to them like all the wires in the harness are bad.[Quick preventative:] Watch the wires coming from the connector directly under the windshield below the driver and the oil pressure and alternator wires on the right front of the motor. These are the first ones to go. If it starts reroute the alternator wire first as this can cause the most damage if left in the harness. Then replace the starter, then the coil wire as these have the next greatest potential for damage. If you can, get the wires replaced before they cause other damage, do so as the cost will come out of your pocket.[1983-1987 7xx cars:] If you are referring to the problem of wiring harness rot that affects the 83-87 models, it usually affects the harness on the engine. On the LH cars, this usually includes a fuel injection harness and a separate ignition system harness. However, I have seen some deterioration of other underhood harnesses including the wiring that goes to various lights (turn signals, corner markers, headlights, etc.[Advice on replacement:] The engine wiring harness went bad on my 1983 240 Turbo (170,000). I noticed it first when my starter would try to engage occasionally when I hit a bump or turned a hard right. The wires up by the firewall on the left side of the car were bare at the connector. I tried to separate and tape them, but that did not work. I found out why when I replaced the harness. The harness runs along the left side of the block, and EACH of the wires was completely bare the majority of the length of the block!! As you know, depending on which ones touched which, anything could happen. REPLACE the whole harness!!!!!! Trying to patch it will only lead you into hours and hours of nightmares both as you attempt to cob it together, and as soon as moisture gets in your cheesy butt connectors and your gauges, idle, starter, etc go wacky!!!Remember: My Volvo is Turbo. Although a similar process, I can not speak directly on the naturally aspirated version. The job took me (a former diesel mechanic but working with limited tools on this job) 5 hours. I unbolted the intake and pulled it away from the head. Of course to do this you will need an intake gasket. I recommend you do this also, as to work around and under the intake would be treacherous. With the intake pulled away, you can see straight down in there. You may want to replace your flame trap when you are in there as you have a straight shot at it. Any troublesome vacuum lines could easily be swapped out also.The new Volvo harness is color coded exactly as the original. (big advantage). It is also exactly correct in length. (huge advantage). Just remove the old one, being careful at each connection - temp sensors, alt, oil press, etc. are all very dry. You may have to cut the old harness out in pieces as it is not pliable at all. Install the new one by starting at firewall and working your way along the block and around to the oil press and alternator. It is pretty self explanatory really. Leave about 5 hours to do it. This sounds like a lot, but multiply it times the hourly rate of your local shop, or the cost of burning up a starter (and a tow) like I did, and you will have a little more incentive to clear up some time on Saturday morning. No special tools. (May want torque wrench for intake if you are REALLY particular). I shopped all over and I purchased it from NILS SEFELDT Volvo in Houston Texas (281) 721-1600 (800) 468-0041 fro $230.22 and the gasket for $11.70. [Additional tips from Dick:] My suggestion: do not remove the intake manifold on the 700 series. Remove AMM and hose to intake, idle speed motor and hoses, also flame trap and oil trap. Label stuff carefully. Begin your rewire from under the car, ie the oil pressure sender light, removing the old stuff as you go. Your new harness has yellow bands indicating where the clamps should be. Remove the harness from the AMM and replace with new. You will have to remove the knock sensor wiring and mark it . I think you get the picture. With the oil trap removed, you can clean it and put a new O ring on it (leak source) and new flame trap. Other suggestion is to remove the 3 plug ins on the passenger side and pull then through and under the manifold along with the injector harness stuff.Believe marking and labeling is extremely important. I blew the brains out of a 240 by mixing up two similar 3-prong connectors. Label the old harness too because you can always compare wire colors in the connectors that are alike.[More from a VCOA Wiring Clinic, courtesy of the BrickBoard:]Scope: The problem afflicts 200 and 700 series Volvos manufactured during the period 1983-1987 [Note: several commentators would also include the 1981 & '82 models of 240 series.]. The problem has also appeared in other vehicles manufactured during the same period with Bosch electrical systems. Owners of all vehicles manufactured with Bosch electrical systems during the period should inspect the engine wiring harness. Anyone considering purchase of such a vehicle should inspect the engine wiring harness if the harness is the original.Presentation of problem: Disintegrating insulation on wires exposed to high temperatures for long periods (10 years or more).Symptoms: All vehicles within scope are vulnerable to the problem. Close inspection of the engine wiring harness will reveal the problem before it causes short circuits. If a vehicle within scope exhibits drivability problems that are intermittent and cannot be otherwise diagnosed, short circuits in wiring harness caused by deteriorating insulation may be the cause.Inspection: Use a strong light source and check wiring, paying particular attention to wiring passing close to high heat sources. High heat sources include intake manifold, exhaust manifold, turbocharger, block, firewall.Common locations presenting problem: B23: firewall near main connector, alternator, intake manifold. B230: ground wires on intake manifold, oil pressure sender, water temperature sensor on block. B28/280: no engines were available for inspection.Solutions:Temporary solutions: liquid electrical tape, applied in several coats over several hours, good between -20 and 255 degrees F; shrink-fit insulation, applied with heat gun or torch, good past 400 degrees F, but hard to fit correctly over end connectors; spliced wiring, recommended by some Swedishbricks and SAAB list members as the most nearly permanent fix that does not require a new harness. Standard electrical tape is at best a one-month reprieve. Any solution short of splicing lasts no more than a few months.Permanent solution: new wiring harness, cost ranges between $250 and $350 (US). VCOA has been successful in persuading Volvo to lower the price of its wiring harnesses for vehicles within scope, and current price range quoted above reflects those reductions. Prices have been cut from 33%-50% from previous levels (Example: old price of engine harness for B230FT engine was approximately $500, now reduced to $270). Dealers who offer club discounts will add their standard discount to the current prices. It is absolutely critical that you order the correct harness. Very difficult to do when there are 3-4 variants out there, yet little way to tell the harnesses/engine applications apart.Workability: Owners who prefer to have a mechanic install the new wiring harness can expect to pay 4-6 hours of shop time for the job. Owners who prefer to do the job themselves should set aside one or two days. For the B230 engine, it is recommended that the owner have all vacuum hoses replaced at the same time, as well as fuel injector seals. In addition, performing the job on the B230 engine involves removal of the intake manifold and air intake valve, and so requires replacement of the intake manifold gasket and the air intake valve gasket. Owners who have replaced wiring harnesses of B23 and B280 engines may wish to offer advice on other maintenance that should be performed at the same time, as well as other parts (besides the wiring harness) that may be required. Dielectric grease for multi-pin connectors, as well as an oxidation inhibitor for single connection points to aluminum ground, are recommended. Do not interchange the two, as dielectric grease is an insulator, while oxidation inhibitor is a conductor.Picture References. Check outhttp://www.homestead.com/volvo2/harness.htmlfor visual images and instructions for wiring harness replacement and other maintenance items.

Maintaining Chassis Grounds. [Query:] What do I have to do to keep the grounds in my chassis circuits in good condition? [Response 1: Steve Ringlee] This is tough to do without the pictures in the Volvo OEM wiring diagram book (the best $25 I've ever spent, by the way) but here are the grounds for my 1990 745:Battery chassis near the battery: often corrodedEngine main ground under the p/s pump (typically OK because of oil coating)Right auxiliary chassis ground (behind right headlamp): frequently corrodedLeft auxiliary chassis ground (behind left headlamp): also usually corrodedInside left A-pillar: underneath the trim panel by the bottom front left door hinge;Inside right A-pillar: just beneath the engine computer by the right front door pillar; this is important since so many functions ground here and humidity/salt can affect it from the carpets.Left and right taillight groundsOn the right console between the seats: not a problemCourtesy lamp ground above the left B-pillar; not a problemFuel pump and sensor ground next to sending unit on fuel tankSRS ground beneath the driver's seat next to the crash sensor. It goes without saying that if you are going to touch this, you need to disconnect the battery negative and wait some time for any charge to dissipate from the crash sensor.[Response 2: Don Willson] One ground connection you missed Steve. Though it has nothing to do with air bags it will cause major running problems. That is the injector ground wires. Just cleaning them and tightening the bolt is not enough. The wire must be soldered to the crimp lug. The internal resistance of this crimp increases until injectors start to missfire, the O2 sensor sees too much oxygen and feeds the engine much too much fuel. Mileage drops to 10 mpg with smoke and no power.These grounds, if corroded, can play havoc with your car's electrical system. A lot of the problems brought up in both Brickboard and Swedishbricks forums relate to faulty ground connections. It pays, especially for those in wet or salty climates, to clean and de-oxidize the ground connections (DeOxIt from Caig Tools is great, at electronic stores) then coat them with OxGard conductive paste (get it at Home Depot) which is designed to protect electrical connections where conductivity is important and shorts across circuit connectors are not a problem.For a good overall discussion of Volvo electrical system grounds, see the article Volvo Electrical System Service: In Search of Good Grounds, Bob Kraft, ImportCar magazine, December 1997 athttp://www.underhoodservice.com/(see their searchable archive for ImportCar Magazine.)

Dielectric vs. Conductive Grease to Protect Connectors and Grounds. [Query:] You have repeatedly recommended the application of dielectric grease to underhood wire connections. Isn't the insulating property of such grease counter to the goal of IMPROVING the integrity of electrical connections? I would think that a conductive paste (such as Eastwood's Kopr-Shield) would be better. The only potential downside I can think of is that sloppy application could cause short circuits, but care and common sense should preclude this. [Response:] This is a good question and one that I have received several times. Yes, it is true that the dielectric grease is non-conductive. However, in the context of connections that carry voltages larger than 1 volt, the grease will not result in a bad connection. The male and female connectors will wipe enough of the grease off at the mating surface so that the electricity will flow just fine. The important part is that there is no chance of the grease creating a conductive path between adjacent terminals in a multi-terminal connector. The main purpose of the grease is to seal the terminals against oxidation which creates a high resistance barrier and moisture and dirt which can result in shorts and ground paths.It is important to note that on all Volvos, the Oxygen sensor signal lead carries a very low voltage (0.2v - 0.8v) and the dielectric grease must NOT be used on this lead as it will interfere with the signal voltage.For the GROUND connections - especially those in the engine compartment where the ground leads are fastened to aluminum surfaces like the intake manifold, I recommend using one of the conductive greases like OxGuard. These are found at electrical supply houses and are typically used by electricians to treat the end of aluminum electrical cables to prevent the very high resistance aluminum oxide from forming at connections - this was a common cause of house fires. The same high resistance oxide plays havoc with engine management system signal voltages. You can eliminate the problem by cleaning the aluminum surfaces and treating with the conductive grease. Also note that many of the spade type crimp on terminals that are available are made of aluminum. It is very difficult to find copper ones. [Note: see also the note on greasing connectors under Engine Tune, Performance.] DON'T use OxGuard on engine or chassis electrical connectors or sensors.

Circuit Board and Contact Repair. [Tips from Joe Ward] My rear taillight has been blowing the bulb rather frequently. Upon a closer inspection I noticed it had worn the copper trace where the lamp holder contacts the copper trace. I removed lamp holder, lightly sanded copper trace areas with some 600 grit, cleaned with alcohol, applied a thin film of conductive epoxy on all three copper traces and let dry overnight. Next morning it was hard as rock and conductive! This product was found at a local electronics supplier (it was near the check-out counter and it occurred to me this would be a good product to try before replacing). Product is used for field repairs for circuit boards that have cracked or broken traces and soldering not available. Cost ~8.00 for tube but it didn't take much. [Tip from JohnB] I had a similar problem with the plastic/copper circuit board below the steering wheel on my Saab. So I sanded the copper circuit and placed about 5-6 strands of copper from some 12-gauge multi-strand twisted together and flattened onto the copper on the plastic and using a 350w Weller soldering gun and electronic rosin core solder, just flashed the copper/wires together

Power Windows Operate in OFF. 1986 740: I just noticed that my power windows work without the key in the ignition. [Response:] a stuck relay would do that. Either that or there's a hot short at the relay socket or in the wiring between the relay and the ignition switch. Should be leftmost relay in the front row. It also powers the electric radiator fan, so given a hot engine on a hot day it too could run when the key is out. A hot short between the relay and the fan thermostat would also enable the power windows. Try tapping on the relay to see if that doesn't at least make a temporary difference. If that helps then you may be able to salvage the relay by opening it and using contact cleaner. If not, then pull the relay anyway and inspect socket for evidence of shorting. After that it's either try a new relay or start tracing with a multimeter.

Relays Run Hot. 87 740 B230F 120,000 miles. Problems with the 740 fuel pump and headlight relays are well documented. Volvo has a tech. bulletin that recommends replacement of the relays and the sockets, which have both been done to my car before I purchased it. Driving today, I put my finger on the fuel pump relay and it was darn warm. I could just hold my finger on it - any hotter and I wouldn't be able to. Is this normal/acceptable? If no, what's the fix (another relay??). [Response:] Relays on Volvos run hot. That's why I drill holes in the covers. You must first remove the circuit board to drill the cover. On overdrive relays, I have never had to replace a relay with holes in it, it seems to help a lot. I have also run cooling to the relay/fuse board from the crotch cooler port, so when the A/C is on, it blows cool air on the board via hose. It may help and can't hurt. [Another:] I've seen several instances on 740s of excessive contact resistance at the fuel pump relay connector. This causes overheating and melting of the spade connectors and plastic socket. It probably wouldn't hurt to examine the male spade connectors and socket for signs of high resistance and overheating (discoloration of metal, melted or burned plastic). [Another:] Your description of the innards of the fuel pump relay sounds right.... the wires from the solenoid coils to the PCB are small and fragile -- but I've never experienced them breaking (at least, breaking from vibration). Because they're fragile, fingers off! Soldering the PCB is done on the other side from the components. You'll notice the component leads (including the fine wires) stick through and are soldered to so-called "traces". These traces are copper, but are usually completely covered by solder so have a silvery color. You'll also see where larger tangs stick through and are soldered -- these are the heavy-current leads from the relay contacts as well as the relay connectors.I usually solder the heavy connections using a soldering gun (but carefully, because these deliver a lot of heat quickly, and can damage a PCB). The smaller solder connections are best done with a small 25-Watt iron. Of course, you must use electronic solder, not plumbing solder (which contains an acid-based flux).

Slow Battery Discharge. See the "Starting" section for more information.

Multiple Electrical Failure: Ignition Switch Bad. [Query:] After stopping our '90 745T the ABS light came on, the blinkers did not work, along with the power windows. Wife managed to get home and call me at work. My first reaction was, of course, a fuse. But when I got home and started up the car, everything was fine, along with the fuses. Any ideas on a solution to my quandary? [Response: Abe Crombie] The electrical switch behind ignition lock is almost certainly the culprit. You can test for this by starting car and then turn key a few degrees either way and see if you can't duplicate what your wife observed. The switch has the spring in it that returns the key to run position after you go to the starter position and it can weaken or wear. The switch is easy to change and is readily available through a good parts supplier.

Cruise Control Surges: Worn Servo. [Query:] What is the fix for surging with the cruise control ON. It tends to fluctuate 2-4 mph in level driving conditions. Real annoying. [Response: Abe Crombie] Look closely at the servo on the throttle housing that tugs the cable wrapped around the throttle spool. This can get a hole worn in it and the vacuum level that keeps throttle positioned evenly is impossible to maintain.Remote Car Starter Installation Guide

NOTE:The information on this sheet is provided to you on an "as is" basis with no representation or warranty of accuracy whatsoever. It is the sole responsibility of the installer to check and verify any circuit before connecting to it. Only a computer safe logic probe or digital multimeter should be used. Dr.Detail and/or any other associated or unassociated individual or corporation who furnishes this document assumes absolutely no liability or responsibility whatsoever pertaining to the accuracy or currency of the information supplied. The installation in each and every case is the sole responsibility of the installer performing the work and/or any other associated or unassociated individual or corporation assumes no liability or responsibility whatsoever resulting from any type of installation, whether performed properly, improperly or in any other way. The information supplied is a guide only.

REMOTE STARTER INSTALLATIONThe following information is provided as a reference guide for remote starter installation. We will discuss the most common characteristics of the wires you must locate and connect to in the vehicle for this type of installation. As always, we recommend that you use a digital voltmeter to perform all wire tests. Test lights can seriously damage vehicles on board computers and cost you big $$$. We also recommend that all wiring connections be soldered to assure a solid lasting connection. Avoid routing any wires near any sharp objects under the dashboard, pay special attention to wires routed through the firewall. Split looming is a good idea for wires running through the engine compartment, if you don't have any available to you, taping the full length of the wire will also add some protection.

Before getting startedWhen a customer's vehicle enters your installation bay you should take a few moments to give it the once over. Check all the switches and systems in the vehicle as well as the exterior lights to make sure that they are working properly and report any defect to the customer before beginning your installation. In the case of a remote starter installation you should also listen to the engine to make sure that it is running properly.

Ignition switch wiringThe major connections for your remote starter are done at the key switch, IGNITION, ACCESSORY, STARTER and in most cases POWER. These wires are usually easy to find, coming off the vehicle's ignition switch. These wires are typically large in gauge however; they can be small gauges as some cars use these wires to control remote relays for all the vehicles operations instead of the wires themselves.

Power wireThe power wire for your car starter should be connected either directly at the battery or to the wire that supplies power to the vehicle's ignition switch. Some vehicle's have more than one wire supplying the key switch but may be fused differently. A good example of this is the dodge intrepid, there are 2 constant power wires at the ignition switch, both are the same gauge, RED & PINK/BLACK. The RED wire is fused at 20 amps and the PINK/BLACK is fused at 40 amps, connecting a remote starters power lead to the RED wire would eventually result in a blown fuse as most remote car starters draw much more than 20 amps. If your remote car starter has 2 power wires you can connect 1 power wire to each of the vehicles power wires. Determine which one is used to supply the accessory output and connect that wire to the power wire that can handle the higher load.

Ignition wireThis wire supplies power to the vehicle's ignition system and fuel pump, it shows between 10 and 14 volts with the key in the RUN and CRANK positions of the key switch. Some vehicles have more than one ignition wire; all ignition wires should be connected when installing a remote starter. Use relays for connecting additional ignition wires.

Second Ignition wireSome vehicles have more than one ignition wire; all ignition wires should be connected when installing a remote starter. Use relays for connecting additional ignition wires. This Second ignition wires must be connected to an additional relay andcan not be tied in with the original ignition wire. Just connect the new relay using the first ignition relay negative trigger wire and connect the B+ to a known good 12V source.

Accessory wireThis wire supplies power to the vehicle's blower and heater/Ac controls. It shows between 11.5v and 14v with the key in the ACCESSORY and RUN positions of the key switch. Some vehicles have multiple accessory wires to control all the heater and a/c functions. If it is necessary to connect a second accessory wire, use a relay!

Starter wireThis wire supplies power to the starter solenoid to crank the engine. It shows between 11.5v and 14v with the key in the START position of the key switch. Many of today's vehicles have a second starter wire which control a sensor that help starting in cold weather, this wire should always be connected. If it is necessary to connect more than 1 starter wire, use a relay!

Parking light wireThe wire that supplies voltage to the vehicle's parking lights can usually be found at the vehicle's light switch or in the harness of wires going to the rear of the vehicle. This wire shows voltage when the parking lights are turned on. Some vehicles have independent left and right parking light wires. Diodes will be needed to isolate the 2 wires from each other. Some Volkswagen cars need to have the parking light wire isolated from the light switch or the wipers and heater will come on when voltage is applied to the park light wire.

Brake wireThis wire can be found at the switch harness above the brake pedal, it shows between 11.5v and 14v when the brake pedal is depressed. This wire can also be found in the harness going to the rear of the vehicle or at the brake light itself.

Ground wireProper connection of your ground wire is essential for your car starter to function properly as it relies as much on this wire as it does on the Tachometer wire to start the vehicle properly and read tachometer pulses. This wire should always be connected to a clean unpainted metal surface in the kick panel or firewall. Grounding directly at the battery terminal is not recommended.

Tachometer wireYour remote starter requires a tachometer reference signal to monitor when the vehicle has started so it can disengage the starter. The vehicle's tachometer reference wire can usually be found on the engine distributor or coil pack or at the ECM (power control module) or PCM (power control module). References to these modules are often found in Wire Magic. First look for the vehicle's ignition coil or coil pack by following the spark plug wires (if possible) to where they junction together at a distributor. You can usually located a small wire harness at this location were a tachometer reference can be found. If the distributor appears to be supplied via a spark plug wire from another module this will be the coil and will also have a tachometer reference wire. A fuel injector is also a source of tachometer pulses, however this provides a signal for only 1 cylinder so make sure the car starter you are installing can be programmed for this setting. Tachometer reference can almost always be found at the vehicle's computer but this is not always easy to access, see the vehicle's data sheet for the recommended tachometer wire and location.

Factory securityMost factory installed security systems can be disarmed by turning the key in the driver's door to the unlock position. In these cases there will be a wire coming from the door that can be pulsed to shut the security down and allow the vehicle to start without tripping the factory alarm system, this wire can usually be located in the kick panel. If the security system does not disarm with the key, check the vehicle's owner's manual or e-mail us on the vehicle you are working on.

Passive anti-theft systemsSome vehicle's are equipped anti-theft systems that are based on security against tampering with the ignition switch and hot wiring of the vehicle such as GM's PasskeyV.A.T.S, Passkey 3, Passlock I, Passlock II or Ford P.A.T.S similar systems found on other makes and models. See the "Factory Anti-theft Bypass Reference Guide" list for details on all these transponder based systems.

Always make all your connections before installing you main power fuse and be sure to program and test all functions properly before closing up you installation.

In closing Use tie wraps or screws to properly secure the starter module and keep the wiring away from any moving parts such as parking brakes or steering column shafts. Mount any switches in a good accessible location where they won't get kicked or hit accidentally.

Take the time to properly explain all functions and features to the customer before they leave the premises. Most comebacks are the result of misunderstandings about how a product works or performs. Doing this will save time and money.How to Install Spotlights on Your VehicleHave you ever tried to install spotlights on your truck or SUV and they just don't work, or they just won't work right. When you buy some new spotlights most of them come with all the wiring and tools and the instructions you need to install them but they have about four different languages on them and they don't make any sense at all. Now this is about the time you decide to forget the instructions and try to make it work your own way right? Well now with these instructions you can easily install your spotlights without all the trial and error.Steps

1Separate all parts, wires, and get the appropriate tool.Ad

2Disconnect the battery.Remember to disconnect the negative terminal first.

3Find the wire that has the fuse build into it, strip your wire on the end closest to the fuse and clamp the terminal connector to your wire.

4Connect the same wire to either the battery (recommended) or a positive 12 volt lead in the fuse box (NOT Recommended ... Reason: If connecting to a 12v lead in the fuse-box make sure that it is capable of powering the lights ie. If You have 2 150w spotlights (12.5 Amps each) And the 12v lead in your fuse-box has a 20amp fuse in-line, you risk melting the plastic and it could result in fire and/or damage to other electrical components, Replacing the fuse with a higher capacity one DOES NOT fix the problem)

5Run the wire into the inside of your vehicle (keeping it away from anything it could be damaged by) run it to the desired place for your switch, connect it to the positive prong on the back of your switch.

6Fasten the switch in the place you want it to be.

7Know that if you are using a switch with any sort of light, you need to the ground prong on the back of your switch to the frame or another spot without paint that is connected to the frame.

8You should have another wire left(which is not black) this wire needs to be connected to the last prong on the back of your switch and ran out of the vehicle to your light, connect it to the white yellow or blue wire from your light.

9Bolt your light tightly to the desired place outside of your vehicle.

10Connect the black wire from your light to the ground of your vehicle.

11Connect your positive terminal back to your battery.

How To Make Your Car Sound Like a Freight Train71,468

Benjamin PrestonFiled to:PARKING LOT MECHANIC 11/23/12 5:00pm

The massive land yachts of the that rolled off of Detroit assembly lines until about 1980 are mostly gone. Mostly, that's a good thing. They handled like crap, took up a lot of space in parking lots, and guzzled gas.But they had a certain, uniquely American charm. They were roomy, commanded attention, and oh the mighty songs played by their horns! Newer cars, while cheaper to run and easier to park, lack the harmonic, train-like boom produced by an old Cadillac's quartet of horns.Your car may have a wimpy little horn, but that doesn't mean you have to settle for it. Here's how to make your horn sound withthe power of Brnnhilde's Immolation.

I had a weak horn problem in my beat up mid-'80s Subaru actually, the horn didn't work at all so I decided it was time to give my anemic econobox the powerful voice of a malaise-eradiesel locomotiveCadillac. Now, when I hit the tiny red button installed on the dash, heads snap toward the huge sound coming out of my relatively small Japanese car. Like many other Americans, I have have a penchant for pointless noisemaking, so only a horn fit for a pimp passes muster.If loud, obnoxious awesomeness is what your life is lacking, here's what to do to give your puny-horned car the voice of a true behemoth:Finding horns:Time for a trip to the junkyard. Horns from any big car will do, but if you're the type who'll settle for nothing less than the best, go for the four-note train horn from an old Cadillac or Buick. GM's two-note horns were loud, and the four-note setupridiculouslyloud. Cadillac used them on most of their cars until about 1980, then on the DeVille until about '85 (when the DeVille became a mid-sized specter of its former self), and they were also in Fleetwoods and Buick Roadmasters until the early '90s. Make sure you have all four notes A, C, D and F. The note is printed near the bell of each horn.Electric parts:To make your faux train horn work, you'll need to put in a button somewhere. Youcouldwire it to your car's stock horn button, but I just wired in a different switch for easier installation, and because I wanted to have the option of using the car's normal horn if I ever decide to fix it. You can get all of this stuff from Radio Shack. You'll need a single-pole-single-throw, normally open momentary switch, a 30-amp automotive relay, a 15-amp inline fuse, and some 16-gauge wire (enough to reach the mounted horns, the car's battery, the relay, and the switch on the dash).

Mounting the horns:Luckily, GM horns only have one wire coming out of them. As long as you bolt them to a patch of bare metal, the ground is all taken care of. On my car, there's a lot of space in the engine bay, so mounting all four horns near the front was easy. In some cars, you may have to drill holes somewhere and bolt the horns up under the bumper or next to the radiator. Just make sure you don't drill into the radiator or a bunch of wires or something. That'll ruin your day.Wiring:Once the horns are mounted (assuming they're mounted in roughly the same place), you can run their wires together into one, then run a jumper from that junction through the firewall (if you're planning to mount the relay inside the car like I did).Take a look at the wiring diagramshown here to see how to connect the horn's hot wire to the switch, the relay, and the battery. You can use an awl or pick to pry open a space in one of the firewall wiring harness grommets to feed your horn wire through. For a hot lead, pick a power source that's hot when the ignition is on or off, so that you can honk at people when the car is keyed off. I put the relay behind the dash, but you can put it anywhere that's dry and relatively cool.Button placement:This is more important than you might think. You should definitely go for as large a button as possible (so you're not fumbling around for the button when you need to fend off potential collision recipients), and try to put the button someplace where you can reach it easily, with one smooth motion of your arm/finger. I put mine right below my stereo, near where my hand goes anyway to change the volume. The rest is training your arm to jab at something other that the center of the steering wheel when you're threatened/pissed/trying to get someone's attention.

Once you have it all together, test it out. Feels good doesn't it? You might not be driving a huge Cadillac, but that's a horn that would make Super Fly beam with pride. And the best thing? You can get everything you need for less than $30 if you shop around. Nothing you could get in a kit from J.C. Whitney would be that cool (except maybe for theLa Cucarachaair horn set), and parts supplier stuff costs a lot more.If you end up trying this out, please post a video of your new horn and the reactions of innocent bystanders in Kinja. Because that would be awesome.CHOOSING AN ELECTRIC FAN CONTROLBy Jim Clark (The Hot Rod MD)

For many years the most effective means of cooling the engine at slow speeds and when idling was with a multi-blade fan attached to the front of the water pump pulley. It drew air through the radiator when the forward motion of the vehicle was too slow to create enough airflow through the radiator. The addition of a shroud helped to funnel the airflow through the full face of the core thereby increasing the cooling effect. However, it is not necessary for the fan to operate at times when the vehicle is running at highway speeds. If it did, the engine would most likely never reach proper operating temperature and the parasitic loss of power could significantly lower operating efficiency.

To remove this power drain a fan clutch was added to disengage the fan so that it freewheeled at highway speeds when the airflow was sufficient. The installation of big engines in small engine bays created a problem though; room for the traditional fan/shroud combo was limited. The most popular solution for this was to install an electric fan and thin-line shroud in place of the mechanical unit.

Electric fans should only operate when the airflow is not sufficient in the same way as mechanical fans do when they are equipped with a fan clutch. Electric fans dont use a mechanical means of disengagement though, they are just turned on or off with either a temperature sensing switch installed in the coolant flow or by a toggle switch controlled by the vehicle operator.

Components to accomplish this can be bought at the local parts store but the job is made easier when one of the many fan control kits is utilized. We chose to use the fan control kit from Spal to control our Spal 16-inch fan on our Cool Craft custom shroud installation. It is offered in two different models; designed to engage at either 185F. or 195F. Deciding which one to use requires the answers to a number of questions about your cooling system.

First you must determine which type of cooling system that you have.

Closed-type cooling system. The closed-type system doesnt vent excess coolant to the outside when the heat causes expansion of the coolant. It has a coolant reservoir that collects coolant that has expanded with the rising temperature of the coolant and would otherwise overflow from the system. When the system temperature drops, the coolant is drawn from the coolant reservoir back into the radiator by suction created by coolant contraction thus maintaining a completely filled radiator.

This cycle occurs when the coolant reaches a certain pressure in the radiator regulated by the spring holding the overflow cap closed in the filler neck. The pressure of the expanding coolant overcomes the tension spring in the cap and allows the excess coolant under pressure to overflow into the expansion tank, or recovery tank through the overflow port in the filler neck.

In a closed-type system care should be taken when checking your coolant level in the radiator. After initial fill up, the radiator is full and the cap is installed, all level checking should be done at the expansion tank. As the cooling system goes through its heating and cooling cycles, coolant needed to replace air trapped in the system will be drawn from the expansion tank. This is where you add coolant if the system is low. Removing the radiator cap will result in loss of system balance and it will take another heating/cooling cycle to reestablish this balance.

Open-type cooling system. Early vehicles with narrow radiators placed the tanks at the top and bottom of the core. The filler cap was placed on the top of the top tank. The radiator was filled with coolant to within one to two inches from the top of the tank to allow for expansion of the coolant. When these systems were pressurized by adding a pressure release cap to the radiator, excess coolant created from expansion was vented to the outside. An over flow catch can was installed instead of dumping this excess coolant onto the ground. However, the coolant is not drawn back into the system as it is with the closed system. In street applications, an upright radiator (top and bottom tanks, with the cap on the top tank) represents a compromise that will work, as long as the car is not operated at sustained high RPM, like those seen in racing.

Radiator CapsThe radiator cap is often overlooked in common engine overheating problems. It is designed to add pressure to the cooling system and increase the boiling point of the coolant. That is accomplished through the use of an internal spring-loaded pressure relief valve. Which one to choose depends on the type of system your vehicle is equipped with.

This is a typical pressure release-type radiator cap with a spring-loaded internal cap designed to lift when reaching a predetermined pressure within the cooling system. Early cooling systems would use a cap that released at 4-lbs. while most modern hot rod cooling systems are set for 15 to 20-lbs

Top Mounted Radiator Cap LocationIn a cooling system, a higher pressure equates to a higher boiling point for the coolant. Higher coolant pressures also transfer heat from the cylinder heads more efficiently. It is recommended that a radiator cap be used with the highest pressure rating that the radiator is designed to accept. The coolant will typically only build to 16-18 PSI, due to expansion up to 200F. However, if the engine does overheat due to external factors, the pressure inside the cooling system could reach as high as 28 PSI. Once the radiator cap has opened and vented coolant, the engine will not cool down until it has been turned off and more coolant added. The radiator cap is basically a "safety valve", so always use the highest-pressure radiator cap that the radiator will tolerate. If you are unsure of the pressure rating for your radiator, check with the manufacturer for the maximum recommended operating pressure.Cross flow Radiator Cap LocationCrossflow radiators with the tanks located on the sides of the core are used in closed systems. The radiator cap should always be located at the highest point of the cooling system, and on the low-pressure side (after the radiator core). Cross flow radiators mounted higher than the engine are ideal because the cap is on the tank that is connected to the water pump inlet. This configuration offers three advantages: 1The cap is at the highest point of the system, allowing any air to migrate to the area just below the cap. In the event the cap vents due to excessive pressure, the air will escape first. 2 This area has the lowest velocity within the system, allowing air to separate from coolant even at high engine RPM. 3 The cap is located on the low-pressure (suction) side of the system, so it is unaffected by the pressure generated by the water pump.

Water Flow ThermostatsThe thermostat is a temperature-controlled device installed into the cooling system that opens and closes to regulate the flow of coolant into the radiator. It opens the valve in the thermostat allowing coolant flow at a predetermined temperature and closes halting flow when the coolant temperature drops. Thermostats are available in a range from about 160 to over 200. Older vehicles with open-style cooling systems and classic engines usually use a lower temperature thermostat. These engines operate at lower temperatures and coolant loss can occur in an open system if the system overheats. Newer vehicles equipped with closed systems are operated at higher system temperatures to aid in reducing emissions and do not lose coolant because it is drawn back into the system when it cools. Any aftermarket thermostat housing that mounts the radiator cap directly above the thermostat location, or that mount the radiator cap in the top coolant hose, are not recommended. Both of those housing styles are poorly designed, and will push coolant out of the cap at high RPM.

Coolant Flow Through The SystemOlder vehicles used low-pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Some added restrictors or slowed water pump speed that prevented the coolant from being forced out, and allowed the engine to run cooler. However, vehicles built in the past thirty years have used cross flow radiators that position the radiator cap on the low-pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it.

A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity.

HosesStandard full-size hoses should be used to ensure maximum coolant flow. Using smaller "AN style" hoses can decrease flow that could inhibit proper cooling.

Pulley RatioFor street applications, the water pump speed must at least match the crankshaft RPM, to a maximum of 10% faster than the crankshaft speed.

The Choice for our ApplicationOur application, a 32 Ford highboy roadster, equipped with an upright-style open-type cooling system has to cool a big Buick Nailhead V8 with a small grille opening. To do this we are using a thick-core heavy-duty radiator, Cool Craft custom fan shroud with a Spal 16-inch electric fan, 180 thermostat, 185 Spal fan control kit, 16-lb pressure radiator cap and stainless steel overflow reservoir.

We settled on this combination after considering all of the previously mentioned factors. The key player in keeping our system operating within the proper range is the fan control. Ours engages the fan at 185F and shuts off at 165F. This allows the cooling system to operate within the proper range without overheating at slow speeds or when idling and while avoiding any significant loss of coolant.

Spals fan relay harness kit includes: a fan wiring harness with relay, fuse holder and fan thermostat (sending unit) 185 or 195. Complete illustrated installation instructions make the installation simple.

Wiring diagram includes the following instructions:Mount the relay in a secure place in the engine compartment away from heat sources or on the panel with the main fuse blockwhichever is most convenient.Once this is completed, connect the wires per the diagram and notes below.Red:Connect to the red wire of fan pigtail with pre-terminated yellow crimp.Gray: Connect to thermostat socket (sending unit) with blue ring crimp connector.Yellow: Connect to positive battery terminal using the fuse holder and yellow crimp connectors per diagram.Orange: Connect to ignition switch +12 vdc when engine is in run position. (Hook to constant +12 vdc for the fan to run continuously when the engine is hot even when the ignition switch is off).Black: Connect ring terminal to chassis ground.Fuse Holder: Connect fuse holder inline per diagram within 12-inches of the battery using ring terminal or equivalent.*Note: On medium profile fans use a 20-amp fuse; on low profile fans use a 15-amp fuse.

The thermostat (sending unit) supplied with the kit is an OE type that is designed to mount in the cylinder head of the engine. However any mounting in the water jacket is suitable. In our Buick Nailhead we mounted it in the water manifold on the engine block side of the water flow thermostat. The sensor is 3/8-inch pipe thread so an adapter may be needed in some applications (1/2-inch adapter included in the kit). Do not use Teflon tape on the sensor or you will get poor electrical contact and inaccurate temperature readings.

Grey wire is connected to the thermostat (sending unit) terminal with the blue ring crimp connector provided.Depending on the model, the thermostat (sending unit) triggers the fan on at 185F. and off at 165F. or on at 195F. and off at 175F. A toggle switch can be wired into the system to manually override the cycling of the fan.

Pre-wired connector plugs into fan connector and the red wire is routed to the relay via an inline crimp connector. Black wire from plug is connected to chassis ground.

Our open-type cooling system needed an overflow tank to catch coolant when the system heated up causing expansion. We chose this Speedway polished stainless steel tank that would fit alongside the radiator within the hood confines of our narrow engine bay.

SPEEDWAY Stainless steel expansion reservoir tank with screw-off cap.Heavy WallBillet Screw in CapClear Neoprene SealApplication:This tank is designed to catch overflow from the radiator.It cannot be pressurized.Info:2" outside diameter, 14" nipples-works with any radiator. Stops loss of coolant and prevents pulling air into system when cooling off. PolishedSpecs:Body height: 14Neck and cap height: 1Tube Lengths: Short 1-3/8: Long 2Overall length: 17Mounting holes are 9.375" center to centerInstallation Note:Short tube is for the radiator overflow hoseLong tube is for the overflow / dump hose (vent for the tank)

www.SpeedwayMotors.com

Tabs for mounting the tank were welded onto the left side-strap of the radiator.A MIG welded was used to minimize heat buildup during the process. Short screws could have been used without penetrating the radiator core tubes because the outside rows are usually capped off in the tanks.Check with the radiator manufacturer to confirm this before assuming this is the case in your application.

Top bracket was installed at least 2-inches below the top of the core. The bottom bracket placed to lineup with the bottom mounting-tab on the tank.

This diagram shows the routing for the overflow hose from the radiator filler neck into the overflow tank and the excess overflow tube inside the tank.

Filler neck on the radiator has this overflow port that allows the excess coolant to escape when the coolant expands from engine heating. This happens when the radiator caps inner cap lifts due to the pressure within the system.

Overflow tube within the overflow tank allows the excess coolant to be dumped onto the ground should too much coolant accumulate

Overflow tank fits within the hood line of the engine bay for those who wish to run side-hoods.

So lets open it up and see whats inside.

Ah, yes, thats right, I bought a MegaSquirt ECU from someone on the GRM board. Also included in the box was a wiring harness and the assembly guide for the ECU. Seeing as there are a few wiring decisions to be made, I decided to go through the build instructions and ensure that everything was in the correct place. Everything was where it needed to be except for two things. Considering how many components are on this thing, thats pretty darn good.These two transistors were in the correct places, but they were put in backwards. The curve of the narrow sides is supposed to follow the silkscreened curve on the PCB.

After ten minutes with a soldering iron, solder wick, and a pair of pliers the problem is solved.

While driving the car I noticed that the ABS warning light wasnt coming on when it should (while starting the car) and the ABS wasnt working. So I pulled the gauge cluster and replaced the bulb. Wouldnt you know it, ABS light comes on and stays on.

So it seems that the previous owner(s) had left the ABS broken so long that the warning light actually burned out, nice.I did a couple of hours of research on the internet for why the ABS wasnt working. It turns out that there is a fusible link in the ABS relay under the dashboard breaks after someone jump starts the car backwards. I pulled the relay apart and found this:

The fusible link was broken. The internet also told me that you could solder a couple of wires across the broken fuse with a 7.5-8 amp fuse inline. So I did just that.

Put it back in the car and the ABS light went out and the ABS worked. But I also noticed that the relay was getting very warm while the car was running. So I took the relay apart again and found that one of my solder joints wasnt connected well. In the process of fixing it I accidentally unsoldered another joint in the relay. It happened to be one end of the coil wire and proved impossible to fix. Next run to the salvage yard Ill look for a replacement.Yesterday was the first autocross of the season in my region so naturally I had to go.

It was a lot of fun, but I was reminded how much I hate automatic transmissions in performance applications. I could bump shift it between 1 and 2, but it still felt slow. Overall impressions: the car has lots of body roll, the nearly new all-season tires arent very good (to be expected), the limited slip works well, the engine pulls strong (at least compared to my del Sol), and the seat needs to be lowered and/or the sunroof removed.In two weeks the car gets its daily-driver privileges revoked and we can finally really start digging into it. I cant wait.1995-2002 Toyota 4Runner Fog Light Installation Using Factory Fog Light PrewireI recently installed aftermarket fog lights on a 2000 Toyota 4Runner (Third Generation). I was able to use some of the factory wiring that was already ran for optional factory fog lights.

Under the hood on the driver side, you should be able to locate the fuse/relay panel. The fog lights fuse/relay location are normally clearly marked on the top plastic cover.

The fog lightcircuit istypically fused at 15 amps. If the vehicle didn't comeequippedwith the factory fog lights, there will mostlikelybe no relay in the location. If you look at the relay location you will notice five female spadeconnectors. The two larger spade connectors on the right side are the ones I used (A and B. One should meter constant 12V, the other should meter continuity to the pink wires on the factory fog light harnesses.

The factory fog light harnesses should be taped up behind the bumper. On each side, they are pretty easy to find.

On the factory fog light harnesses you should have two wiresWhite/Black - GroundPink - Goes up to fuse/relay panel in engine bay (Positive)

If you connect your aftermarket fog lights, to the wires at the factory fog light harnesses. White/Black wires should connect to ground wires coming off the aftermarket lights, Pink wires should be connected to the positive wirescomingoff the aftermarket lights. Now when you jump terminals A and B at the factory fog light relay location,you should be able to power up your new fog lights. The fog lights I installed required about 8 amps of current with the vehicle off.

Now all I did was run two wires one from terminal A and one from terminal B, thoughthe fire wall into the vehicle and connected them to an on/off switch.

You will always want to make sure to use a switch that isappropriatelyrated for thisapplication. If I remember correctly I used a switch rated to handle 25 amps @12 Volts.Hope this helps!

Jeremy's Car Audio Tips

Posted byJeremy Travis Vasquezat11:49 PM1 comment:Email ThisBlogThis!Share to TwitterShare to FacebookShare to PinterestLabels:4Runner,ToyotaTuesday, May 21, 2013Volvo XC90 Aftermarket Stereo Installation

If you haven't installed an aftermarket stereo into a Volvo XC90, then you may find this car audio tip helpful.

The stereo removal is pretty easy if you need step by step direction for removal I will post a link bellow.Metra 99-9225 Dash Kit InstructionsAlong with a dash kit, you will also need an aftermarket antenna if you want to be able to get reception with your new aftermarket stereo. I will post a link to the antenna Itypically use bellow.Universal Window-mount AntennaIf your going to be integrating the factory steering wheel controls you will also need a SWC interface, like the one bellow.Axxess ASWC

Moving on, once the stereo/ac control panel is removed you will need to separate the face of the stereo from everything els.Make sure the key iscompletelyout of the ignition switch before disconnecting any wire harnesses.Do not place the key back into the ignition switch until you have reconnected allnecessaryharnesses.

The main LCD display will need to be reconnected and remain in the vehicle to allow the factory components to function properly. In order to make this possible you will first need to remove the LCD display from the stereo panel.

The CD changer portion of the stereo can be removed, and will no longer be used. The main LCD will need to be reconnected and setaside.

This is the CD changer harness. Other than the two orange fiber optics cables there should be three wires.12VConstant- Violet/WhiteSwitched 12V - VioletGround - BrownWhen I wired up the new stereo harness I tapped into the Violet/White for my 12V Constant at this harness, but I tapped into thecigaretteoutlet power for my Switched 12V and ground because I know the cigarette outlet is rated for more current.

The wires coming off the cigarette outlet harness should be,Switched 12V - VioletGround - Black

Once you have connected your main power wires for your stereo, and any accessories like the power antenna, SWC interface, you will need to connect your speakers. The Volvo XC90 I installed this stereo in had what was called the eight speaker system. Some will come with the twelve speaker system, with anoptionalsub. If the vehicle your installing the new stereo in has the twelve speaker system you will need an additional amp to power the additional speakers. Otherwise some speakers will be lost including the factory sub.The speaker wires can be found back bellow where the factory stereo/ac controls mount, in the dash.Front Left Positive - Gray/RedFront Left Negative - GrayFront Right Positive - Gray/RedFront Right Negative - GrayRear Left Positive - Gray/WhiteRear Left Negative - GrayRear Right Positive - Gray/WhiteRear Right Negative - GrayAs you can see you will need to meter and pop the speakers with a 1.5V battery to identify what side the speaker is on.

After locating the speaker wires you will want to cut each pair. One side will be coming from the factory amp, the other side will be going to each set of speakers. You shouldn't need to use the side that runs down towards the factory amp under the passenger seat. The other side should be the side that runs to each set of speakers, you will want to test this side with a digital multi meter. You should get a reading of around 2ohms on each pair of speaker wires. Now depending on the stereo your installing, will depend on how you will want to wire these factory speaker to your new stereo. If your new stereo doesn't support 2ohm speakers, then you may need to wire the front left and rear left speakers in series and the front right and rear right speakers in series to get theimpedance up to around 4ohms. You will lose your "Fade" in the stereos settings, along with some volume and quality but should allow you to power the factory speakers off the aftermarket stereo without adding an aftermarket amp. If you are also installing new speakers then you shouldn't have to worry about theimpedance of the factory speakers.

After you have all your wiring taken care of, you will want to place and secure the main LCD nicely bellow the stereo. I normally rap it in carpet.

That's just about it, sometimes you will have to cut out some of the plastic behind the stereo to get it to fit in just right. One other thing you may want to be aware of is the headphone controls in the back of the vehicle will be lost.

If you happend to trigger theAIR BAG LIGHTthen you will need to get that code deleted at thedealership, or if you want to do it yourself you can purchase a diagnostics tool like this.It is the Autel AutoLink AL619Anyway I hope this helps!

- JEREMY'S Car Audio Tips

Posted byJeremy Travis Vasquezat10:45 PM27 comments:Email ThisBlogThis!Share to TwitterShare to FacebookShare to PinterestLabels:Factory Amp,Stereo Replacement,Volvo,XC90Ford F-Series Super Duty Trucks - Wiring Factory Auxiliary Upfitter Switches

If you are looking to use the factory upfitter switches in a Ford F-Series Super Duty Truck (F-150, F250, F350, F450, F550) then this tip may behelpfulto you.

The 4 factory switches aretypicallylocated on the lower passenger side of the dash, below the stereo.They can be used to power and control additionalaccessories, when the vehicles ignition switch is in the on position.

The auxiliary upfitter switch wires aren'ttypicallythe wires you will clearly see right bellow the driver side steering column.You cantypicallyfind the wires and the relays under the plastic cover, located on the end of the driver side dash.

Once that cover is removed, you should see the black relay pack.

You can remove the black cover to reveal the 4 auxiliary switch relays. The output wires will be located below the relay pack, coming out of factory black split loom.

Near the output wires, you should see a white tag thatidentifiesthe aux output wire colors with the aux switch number.

AUX 1 - YellowAUX 2 - Green/BrownAUX 3 -Violet/GreenAUX 4 - Brown

You should be able to located the fuses for the auxiliary switches in the fuse panel to identify the max current for each switch. I believe AUX 1-2 are 30 Amps, and AUX 3-4 are 10 Amps.

If you need more room to work, you can unclip the relay pack and pull it out under the driver steering column right near the parking brake.

You can also then gain access to the wiring off the back of each auxiliary relay.Hope this helps!

- JEREMYCar Audio Tips

Posted byJeremy Travis Vasquezat3:43 PMNo comments:Email ThisBlogThis!Share to TwitterShare to FacebookShare to PinterestLabels:F-Series,Factory AUX Switches,Ford,Super DutyMonday, May 6, 2013Mercedes Benz ML 350 Overhead Installation

I recently had the pleasure of installing an overhead LCD/DVD player in a new 2013 Mercedes Benz with a sunroof. Not to much different from any other vehicle with a sunroof, just had to really pay attention to details.

I placed the overhead up to the headliner, to get an idea of where it would look and function the best. Once I had an idea of where I wanted it, I checked for clearance by dropping the driver side of the headliner. I then placed the metal mounting plate in the center of the chosen location, and double checked mymeasurements.

Once I had it centered, I traced it onto the headliner.

Time to cut the headliner,I slowly cut the piece of the headliner out with a razor.(Always make sure the sun roof and sun shade are in the closedposition!)

Once the piece was cut and removed, I checked for proper fitment.The back of the overhead mounting plate will be secured to the roofs re-enforcementbracket that runs across the roof of the vehicle. The front will be supported by the headliner.

I riveted a piece of ABS plastic to the front egde of the metal mounting plate. This piece of ABS will rest on the top side of the headliner so when the overhead LCD/DVD player is mounted to this plate the headliner will be sandwichedin-between.

The dome light is a positive trigger system.Constant 12 Volt - Pink/BlackPositive Dome Light Trigger - Gray/BlackGround - Brown

On the back of thecenter consul there should be a power outlet that is switched power.

That's where I tapped into switched power.

I used short steel rivets to secure the back side of the mounting plate to the vehicles re-enforcementbraket. I had a little less then 1/4th inch to work with and using screws was just to risky.One other thing you must be carful with is where you run your wires, I ran mine in the little channel of space I had between the headliner and the re-enforcementbraket that runs across the roof. If you don't run your wires properly you will get marks/scratches on the sun shade.

Once I had my wires run and mounting plate secured, I mounted the overhead and tripple checked clearance.

It was a tight fit but came out perfect!

Car Audio TipsJeremyFuse Panel, Ignition Switches, Etc... How to Wire Stuff Up Under the Dash.How do you wire up the fuse panel? What do you need to do to the dash? How's the ingition switch fit into all this?First you have to figure out what you've got to work with. Are you using an original ignition switch? Is it from an older car? Or are you starting from scratch and have a new universal ignition switch?If you still want to run the original switch, it's probably not capable of carrying enough current for modern needs without seriously limiting the the voltage or burning out all together.However, there is a way to keep it and still use it to power everything.That's right, our old friend the relay.The relay is just an industrial sized switch. With it the older ignition switch can still be used, but now it will simply turn on and off the relay which takes hardly any juice at all... And it's simple to do:

Now if you have a newer style switch, they're capable of handling much more current. However, if you're running lots of accessories, then you still may want to run a relay.Now, to wire up your fuse panel, look at the following diagram. Note that only one wire power wire can run a few circuits on the fuse panel. You use jumper wires. Some aftermarket ones come with them, and others you just make your own.Circuit :Ron JEmail :

Description:This circuit features exit and entry delays, an instant alarm zone, an intermittent siren output and automatic reset. By adding external relays you can immobilize the vehicle and flash the lights.

NotesThe alarm is "set" by opening Sw1. It can be any small 1-amp single-pole change-over switch - but for added security you could use a key-switch. Once Sw1 is opened you have about 10 to 15 seconds to get out of the vehicle and close the door behind you. When you return and open the door the buzzer will sound. You have 10 to 15 seconds to move Sw1 to the "off" position. If you fail to do so, the siren will sound. The output to the siren is intermi