safety interlock systems
TRANSCRIPT
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3-1. GENERAL.
3-1.1 There are two basic electric wiring systemsused: one for battery start models and one forrecoil start models. All safety systems used arebased on the same principle.
3-1.2 Most riders and tractors produced in 1982were equipped with a reverse safety switch.This safety system required the cutting deck tobe disengaged before the unit can be shiftedinto reverse gear. These systems will be usedon all current production units.
3-1.3 The lift and disengagement lever is used toraise and lower the cutting deck which deter-mines the cutting height. Pulling it all the wayback and locking it disengages the blades. Thelift and disengagement lever MUST be in thedisengaged position when starting the engine,when shifting into reverse or if the operatorleaves the seat.
3-1.4 All lawn and garden tractors produced afterJuly, 1987 were requested by ANSI (AmericanNational Standards Institute) to have an opera-tor present as an added safety feature. If theoperator leaves the seat with the blades orPTO engaged, the engine will shut off. Thisseat switch is a safety device, designed foryour protection. See Figure 3-1.
WARNING
NEVER attempt to bypass this operation.
3-1.5 In mid 1986, safety switches were added tomost lawn and garden tractors, internallymounted in the seat.
3-1.6 On 1988 production, the location and type ofsafety switch was changed on most frontengine lawn tractors. It was mounted on theseat bracket under the seat and it will shut offthe engine with the deck engaged, with lessthan 40 lbs. of weight on the safety seat.
3-1.7 The 1990 riders and tractors have incorporateda new seat safety switch. The operator mustengage the parking brake before leaving seator unit will stall out. This new switch will also bepresent on riders and tractors with electricPTO’s.
WARNING
NEVER attempt to bypass this operation.
3-1.8 For further information regarding this section,refer to the Technical Service Video “SafetyInterlock Systems.”
3.2 SAFETY INTERLOCK SYSTEM – CHANGESFOR 1991.
NOTE
The safety interlock system for 1991 has somechanges that may or may not retrofit prior pro-duction units.
WARNING
At no time should the safety interlock systembe bypassed for consumer’s operation or con-venience.
SAFETY INTERLOCK SYSTEMS
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3-2.1 600 Series Rider Only.
1. The PTO safety switch mounting bracket waschanged for added support to 14 gauge steel.This will retrofit 1990 production units. See Fig-ure 3-2.
2. The standard battery used in the 600 series is725-0514 (125 cold cranking amps). This bat-tery can now be replaced by part number 725-1430 (275 cold cranking amps) by removingthe battery spring retainer to allow clearancefor the larger battery. This will not retrofit priorproduction units. See Figure 3-3.
3. Attach the steering wheel and indicator lightpanel as follows:
a. Place the indicator wires through the steeringbellows and place the bellows over the steer-ing shaft.
4. Place the indicator wires through the cable tielocated on the bottom side of the steeringwheel insert. Connect the wires to the corre-sponding wires in the steering wheel insert.
Tighten the cable tie on the insert to securelyhold the wires in position.
5. Snap the steering wheel insert over the fourspokes making sure the indicator lights arepositioned towards the bottom.
6. Tighten the special cable tie in such a mannerso the cable tie can slide up and down the wireharness which goes through the dash panel.(Slide the cable tie up until it rests against thehole on the inside of the dash panel.)
b. Place the five wires through the slotted holelocated towards the center of the steeringwheel hub. With the front wheels positionedstraight forward, place the steering wheel overthe steering shaft. Secure with the cuppedwasher and lock nut provided in the screw-pack. See Figure 3-4.
NOTE
The indicator wires should be positioned at thebottom of the steering wheel (6 o’clock posi-tion).
CAUTION
Do not cut off excess cable tie. The excess endwill help keep the harness from being drawn upinto the steering wheel and causing seriousdamage to the wires.
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7. Turn the steering wheel fully in both directions.Pull the wires down from the dash and slidethe cable tie down an additional 1/4 inch andtighten the cable tie securely. While doing thisprocedure the cable tie will automatically posi-tion itself on the harness to prevent damage tothe wires during normal operation.
3-2.2 All Riders and Tractors.
1. The clutch safety switch has a retainer bracketfor added support. This will retrofit 1990 pro-duction units. See Figure 3-5.
NOTE
If the clutch safety switch (part number 725-3169A) is ordered, it will NOT come with theretainer bracket or screws. To retrofit to a pre1991 production unit, it is necessary to orderthe retaining bracket (part number 179162)and two screws (part number 710-0351).
2. The seat safety switch insulator nut plateshave been redesigned to reduce the chancesof a direct short. This will retrofit 1990 produc-tion units. See Figure 3-6.
NOTE
This boss plate goes all the way through thetwo spring switches and will reduce thechances of a short. This also will retrofit priorproduction units.
3-2.3 600, 700 and 800 Series Only. The circuitbreaker is being replaced by a standard auto-motive type fuse. Nonregulated electrical sys-tems will use a 7-1/2 amp fuse. On regulatedelectrical systems, a 20 amp fuse will be used.This will not retrofit prior production units. SeeFigure 3-7.
NOTE
Although this will not retrofit our prior produc-tion units, there are, however, two separatefuses: the 7.5 amp fuse for a standard dual cir-cuit alternating system and the 20 amp fuse fora regulated system.
3-3. ELECTRIC START SYSTEM.
3-3.1 Before the engine will crank, the key must beturned on and both of the safety switches mustbe activated. One is activated when the clutchis depressed and one is activated when theblade is disengaged. When this happens thecircuit will be complete between the batteryand the coil primary of the solenoid. This willclose the solenoid which will allow the startermotor to crank the engine. The safety switchesare wired in series on the electric start mod-els. See Figure 3-8.
3-3.2 Testing the Interlock System on the ElectricStart System.
1. Starting instructions:a. Disengaged the blade or PTO.b. Depress the clutch pedal.c. Set the throttle (and choke if separate).d. Turn the ignition key to the START posi-
tion.
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NOTE
If the engine does not crank, use the followingprocedure to check out the system. If theengine cranks but does not start, the problemis not with the interlock system.
2. Check the two safety switches to see that thedisengaging of the blade and the depressing ofthe clutch depresses the black plunger a mini-mum of 1/8 inch.
3. Check the fuse or circuit breaker between thepositive terminal of the battery and the ignitionswitch. If the fuse or circuit breaker is blownthe engine will not crank.
4. Check the following terminal to see that thewires are in place.
a. The positive terminal of the battery. A largeand a small wire should be fastened
securely to this terminal. On some unitsboth wires are cast into one clamp.
b. The negative terminal on the battery andthe ground to the frame.
c. The ignition switch terminal.
d. The clutch safety switch.
e. The blade safety switch.
f. The solenoid terminals. A small wire is fas-tened to the coil primary and the two largerwires are fastened to each side.
5. Check the condition of your battery. Even if thebattery is dead you should be able to hear thesolenoid click. This would verify that the start-ing system is operating at least to the solenoid.The specific gravity of the battery should be1.265.
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6. A continuity tester can be used to check thecontinuity between each component of theinter-lock system. Follow the instructionspacked with the continuity tester which can bepurchased at electrical shops.
WARNING
To test the interlock system further, you will bebypassing the safety switches. Make sure thatthe clutch is disengaged and the bladeengagement lever is in the disengaged posi-tion. If the clutch cannot be locked in the dis-engaged position, place the gear shift lever inthe neutral (N) position. When using a jumperwire in the following tests the engine maycrank over.
NOTE
Disconnect the spark plug lead and ground itagainst the engine block
7. Use a jumper wire between the followingpoints:
a. The positive terminal on the battery to theterminal on the solenoid (coil primary). Ifthe engine cranks, then test within this cir-cuit to find the exact area of the problem.See steps b and c below.
b. The positive terminal of the battery and theS terminal on the ignition switch. If theengine cranks, the problem is between thebattery and the ignition switch.
c. The S terminal on the ignition switch to thecoil primary terminal on the solenoid. If theengine cranks, the problem is between theignition switch and the solenoid.
d. Jump between the two large terminals onthe solenoid.
3-3.3 Testing the Safety Reverse Switch on theElectric Start Systems. If the engine can bestarted, but stalls when the blade is engaged,use the following procedure to determine if theproblem is in the reverse safety switch:
NOTE
Only use a wire as heavy as the wire from thesolenoid to the starter with an alligator clip. Ifyou have current up to the coil primary termi-nal of the solenoid and the starter will not
crank, however, you can crank the starterusing the jumper wire, the problem is with thesolenoid. Check the base of the solenoid tosee that it has a good ground to the frame ofthe unit. If it still fails to operate, replace it.
NOTE
Transmission lever must not be touching thereverse spring switch and the key must be inthe ON position.
1. Disconnect the yellow wire going to the mag-neto on the engine.
2. Disconnect the wire attached to the springswitch.
3. Attach one lead of a continuity tester to thespring switch and the other lead to ground. Ifthere is continuity, the fiber washers could bedamaged and should be replaced.
3-3.4 Testing the Solenoid on Electric Start Rid-ers and Tractors.
NOTE
Through examination of returned warrantyparts, we have found instances of solenoidsbeing replaced unnecessarily on electric startriders.
1. The following are real solenoid problems andrequire replacement of the solenoid:
a. Solenoid is stuck – Unit will start with igni-tion key in OFF position.
b. Coil wire (inside solenoid) is bad – Sole-noid will not function.
c. Bad washer (inside solenoid) – Solenoidclicks but starter motor does not turn.
2. Other problems which can appear to be adefective solenoid:
a. Faulty ground.
b. Defective safety switch.
c. Discharged battery.
d. Defective starter motor.
e. Blown circuit breaker.
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f. Defective ignition switch.
g. Defective wire harness.
1. Coil Check:
a. Disconnect the spark plug wire from thespark plug.
b. Disconnect the coil wire from the solenoid.
c. Using a DVOM (in the OHMS setting)attach the red lead to the coil connectionand the black lead to system ground.
d. The resistance reading should be about 5ohms.
*Meter readings greater than 10 ohms orless than 3 ohms indicates solenoid failure.
e. Remove meter leads and reconnect coilwire.
2. Contact Check:
a. Disconnect the spark plug wire from thespark plug.
b. Disconnect the wire AT THE STARTERwhich runs to the solenoid.
c. Using a DVOM (in the OHMS setting),attached the red lead to a contact bolt andthe black lead to the other contact bolt.
The meter should read “OPEN” circuit, orinfinity.
*A “closed” circuit indicates solenoid fail-ure.
d. Energize the solenoid using the startswitch. WARNING: DO NOT HOLD “ON”FOR MORE THAN 5 SECONDS AT ATIME.
e. The meter should read “CLOSED” circuit,or less than 10 ohms.
*An “OPEN” circuit indicates solenoid failure.
f. Remove meter leads and reconnect thestarter wire.
3-4. RECOIL START SYSTEM.
3-4.1 The recoil start system is completely differentthan the electric start system. If the clutch is notdepressed (disengaged) the blade is not disen-gaged or the ignition key is not ON, the ignitionwill be disabled and the engine cannot bestarted. In order for the blades and clutch to beengaged without killing the engine, you mustinsert the recoil starter handle into the dashpanel and turn it a quarter turn. This will disen-gage the wire that grounds the magneto. Thesafety switches are wired in parallel on the recoilstart models. See Figure 3-9.
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3-4.2 Pushing the plunger in breaks the contact ofthe circuit. The red or white plunger identifiesthe switch as being the correct one to use onthe recoil start models. See Figure 3-10.
5 -4. If the engine will not start and the gasolineshut-off valve is open, there is fuel in the gaso-line tank and the spark plug wire is attached,use the following procedure to determine if theproblem is in the engine or the safety interlocksystem:
1. Check the two interlock switches to see thatthe disengaging of the blade and the depress-ing of the clutch depresses the red plunger aminimum of 1/8 inch.
2. Disconnect the yellow wire from the ignitionswitch to the engine where it attaches to theprimary wire from the breaker assembly.
3. If the engine starts now, the problem is withinthe interlock system.
4. Check the grounding system behind the recoilstarter handle. When the recoil starter handleis being pulled, the bolt on the spring should begrounded against the rivet. When the recoilstarter handle is locked in place, the bolt on thespring should not touch the rivet.
3-4.3 Testing the Interlock System on the RecoilStart System.
1. Start the engine as follows:
a. Disengage the blade.
b. Depress the clutch pedal and lock it in thedisengaged position.
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c. Set the throttle control.
d. Turn the ignition key to the ON position.
e. Grasp the recoil starter handle and unlockit by twisting it 1/4 turn. Pull out sharplyand hold it in the out position. See Figure3-11.
f. Slowly let it rewind and pull it out again ifthe engine does not start.
g. After the engine starts, slowly let the recoilstarter handle rewind and lock it into thedashboard by turning it a quarter turn. SeeFigure 3-12.
WARNING
To determine if the problem is in the engine orinterlock system, it is necessary to make themower unsafe by bypassing the safety switches.Use extreme caution in performing these tests.
WARNING
The engine can no longer be shut off with thekey.
2. Disassembly procedure. Disassemble safetyseat as follows:
a. Remove molding clip on lower front ofseat. Remove molding.
b. Remove seat covering and foam padding.
3-4.5 Testing the Safety Reverse Switch onRecoil Start Systems. If the engine can bestarted, but stalls when the blade is engaged,use the following procedure to determine if theproblem is in the reverse switch:
1. Disconnect the yellow wire going to the mag-neto on the engine.
2. Disconnect the wire attached to the springswitch.
3. Attach one lead of a continuity tester to thespring switch and the other lead to ground. Ifthere is continuity, the fiber washers could bedamaged and should be replaced.
3-4.6 Testing Procedure for Operator PresentSystem (Safety Seat).
1. To check the operation of the safety seat, pro-ceed as follows:
a. Start the unit as instructed in the owner’sguide.
b. Set the parking brake.
c. Place shift lever in neutral gear.
d. Engage the PTO or blades.
e. Raise up off seat (this will activate the seatkill mechanism).
WARNING
The recoil start system is not a fail-safe sys-tem. When a wire becomes unplugged fromany component, it does not prevent starting asthe electric start system does. If the engine canbe started with either the clutch or bladeengaged or with the ignition key in the OFF
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position, the unit should not be returned to thecustomer.
NOTE
The transmission lever must not be touchingthe reverse spring switch and the key must bein the ON position.
At this point the engine should stop running. Ifunit continues to run, check wire lead and seatplug for proper connection. If this connection issatisfactory, then the seat switch mechanismand wire lead continuity should be inspectedfor shorts in the electrical system. See Table 3-1.
2. Disassembly procedure. Disassemble safety seat as follows:
a. Remove molding clip on lower front of seat. Remove molding.
b. Remove seat covering and foam padding.
NOTE
Covering and padding are bonded together.
c. Remove phillips head screws, metal plate,bushings and foam pad. See Figure 3-13.
NOTE
When reassembling, note the position of nylonbushings. Shoulder of bushing must be placedupward through plate.
d. Check for broken terminal end or frayedplug wire tape to the bottom of the seatpan.
3. Assemble seat in reverse order. Once assem-bled, check by pushing downward on metalplate. Distance between metal plate and phil-lips head screws must be maintained forproper switch operations.
NOTE
For 1988 production, the location and type ofsafety switch has been changed on most frontengine lawn tractors. It is now mounted on theseat bracket under the seat. See Figure 3-14.
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3.5 TROUBLESHOOTING SAFETY INTERLOCKSYSTEMS.
Problem: The engine will not crank.
1. Check the battery cables to be certain that theyare connected properly. The black cableshould be connected to the negative terminalon the battery. The red cable should be con-nected to the positive terminal on the battery.Connections must be tightened securely. SeeFigure 3-15.
Figure 3-15.
2. Check the battery with a voltage tester. Thebattery should read approximately 12 volts.Turn the key switch to the start position. If thevoltage drops more than 2 volts, refer to thebattery video for testing procedures. See Fig-ure 3-16.
Figure 3-16.
3. Remove the shift panel to gain access to thesolenoid and fuse.
a. Check for a tripped circuit breaker or blownfuse. Circuit breakers seldom open orfuses blow without a reason. The problemmust be corrected. See Figure 3-17.
Figure 3-17.
b. If your unit has a fuse, pull the fuse todetermine if it has blown. If it has, you willhave to find the fault.
c. To test a circuit breaker, connect a voltmeter or a 12 volt test light between thenegative battery terminal and each side ofthe circuit breaker terminals. If voltage ispresent at both terminals the breaker isgood. If not, replace the breaker.
d. Check for a short in the wiring. A deadshort may be in the cranking or chargingcircuit where the insulation may haverubbed through and exposed a bare wire.Replace the wire or repair with electricaltape if the wire strands have not beendamaged.
e. Look for a wire pinched between bodypanels, burned by the exhaust pipe or muf-fler or rubbed against a moving part.
4. If your unit has a dual circuit alternator and thefuse is blowing or the breaker is tripping, checkfor proper wiring. If you have a regulated sys-tem disregard this section.
Disconnect the red and white lead connectorwhich goes to the alternator. If the unit cranks,the wires are reversed and a dead shortresulted. Reverse the wires to correct the prob-lem. See Figure 3-18.
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Figure 3-18.
NOTE
For more information on charging systems, seethe video “Batteries and Charging Systems”.
5. Check to be certain the small orange wire is con-nected to the small terminal on the solenoid. Onsome units, this wire may be red instead oforange.
Using a test light or meter, check for voltage atthis wire with the key in the start position. If volt-age is present, the key switch and safety circuitsare O.K. but the solenoid must be checked fur-ther or replaced. See Figure 3-19.
Figure 3-19.
6. Clamp the test light to the base of the solenoid.Touch other probe to the positive terminal of thesolenoid. It should show voltage.
7. Touch probe to terminal on solenoid that goes tostarter. Turn ignition key to the start position. If novoltage is present, replace the solenoid.
Check to be certain the unit is grounded properly.The black, or negative, cable coming from thebattery must be properly secured to the frame orengine, depending on the model tractor.
8. To check for proper electrical ground, connectone side of your meter or test light to the positiveterminal of the battery. Touch the other lead tothe mounting bracket of the solenoid. If voltage ispresent, the solenoid is properly grounded. SeeFigure 3-20.
Figure 3-20.
Touch the other lead to the mounting bracket ofthe soleniod. If voltage is present, the solenoid isproperly grounded. See Figure 3-21.
Figure 3-21.
If your unit has a small green wire to the baseof the solenoid, make certain that it is securelyconnected.
9. The engine may have a ground wire located atthe base of the engine, attached to the frame.It must be firmly attached to both the engineand the tractor frame. See Figure 3-22.
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Figure 3-22.
10. To test for ground, connect one test lead to thepositive terminal of the battery and the otherlead to the engine block. If voltage is presentthe engine is grounded properly. If not, checkthat the ground wires are clean and properlyconnected. See Figure 3-23.
Figure 3-23.
11. Check for voltage at the starter motor by con-necting one lead to your tester to the engineground. Touch the other lead to the startermotor terminal. Turn the key to the start posi-tion. If voltage is present and the engine doesnot crank, all circuits are working properly andthe problem is in the engine. Contact yourauthorized engine service dealer. See Figure3-24.
Figure 3-24.
12. If voltage was not present at the orange wireon the solenoid while cranking the engine, youwill need to check the ignition switch andsafety interlock switches to see if they arebeing activated properly. There are threeswitches which must be activated in order tocrank the unit: the ignition switch, the clutch/brake pedal switch, and the deck lift leverswitch or PTO switch if your unit has an electricPTO.
Make certain the switch activators aredepressing the plungers on the switches. Also,check for proper wire connection at the switchterminals.
NOTE
13. Check the ignition switch to be certain the wireharness connector is completely secured tothe ignition switch terminals. Wires on the har-ness plug at the ignition switch should beinstalled as illustrated.If the unit still fails to start you will need to testthe ignition switch further.
14. For clarity we have removed the ignitionswitch. See Figure 3-25.
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Figure 3-25.
There is a seat safety switch and a reversesafety switch on this unit; however, they arenot involved in the cranking circuit.
15. Using a test light or meter, connect one lead toground. Connect the other lead to the blackterminal on the ignition switch. Voltage shouldalways be present. See Figure 3-26.
Figure 3-26.
16. Move the tester from the black lead to theorange lead. Turn the ignition key to the startposition. If voltage is present, the ignitionswitch is good. If no voltage is present, replacethe ignition switch. If the unit still fails to crank,continue testing. See Figure 3-27.
Figure 3-27.
17. For units without an electric PTO, raise thedeck lift lever fully and make sure the plungeron the safety switch is fully depressed. Attemptto start the unit. If it does not crank, remove thePTO switch. Using a jumper wire, connectbetween the two orange terminals. If the unitnow cranks, replace the deck lift lever safetyswitch.
18. If you have an electric PTO, remove the con-nector from the PTO switch. Jump between thetwo orange terminals. If the unit now cranks,replace the PTO switch. See Figure 3-28.
Figure 3-28.
19. If the unit does not crank, make sure theclutch/brake pedal switch is fully depressed.Remove the switch and jump a wire betweenthe two orange terminals. See Figure 3-29.
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Figure 3-29.
20. If the unit cranks, replace the clutch brakepedal safety switch.
Problem: The engine cranks but will not start.
1. Check the fuel tank for gas.
2. Check to be certain the spark plug wire isfirmly connected to the spark plug terminal.
3. Check the throttle and/or choke for properstarting position.
4. Disconnect the yellow ground wire on theengine. If the engine starts, the problem is withthe safety switches or wiring harness.
5. If the engine fails to start, and you do not havean afterfire solenoid, the problem is in theengine and must be repaired by an authorizedengine service dealer.
6. If you do have an engine with an afterfire sole-noid attach your tester to the red wire andground. Voltage should be present in the startand run positions. If voltage is not present,replace the ignition switch. See Figure 3-30.
Figure 3-30.
7. Disconnect the wires or harness connectorfrom the clutch/brake safety switch.
With another wire, jump across the two red ororange wires in the harness connector andstart the unit. If unit starts, the switch is defec-tive and must be replaced.
8. Disconnect the yellow wires on the deck liftlever safety switch or PTO safety switch if yourunit has an electric PTO. Jump across the redor orange wires. If engine starts, the switch isdefective and must be replaced. See Figure 3-31.
Figure 3-31.
9. Check the ignition switch by removing the yel-low wire from the switch harness and try tostart the unit. If the unit starts, replace the igni-tion switch. Reinstall the yellow wire to the con-nector to stop the engine. See Figure 3-32.
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Figure 3-32.
Problem: The engine stalls when engaging clutch/brake pedal.
Check both the reverse safety switch and seatsafety switch for grounding out conditions.
NOTE
Wires must not come into contact with the unitwhen checking these connections.
1. Disconnect the yellow wire on the reversesafety switch. With the engine running, placethe shift lever in neutral and release the clutch/brake pedal. See Figure 3-33.
Figure 3-33.
If the engine continues to run, the screws onthe reverse safety switch are grounding outagainst the reverse safety switch bracket.
Correct by removing the screws that hold thereverse safety switch to the bracket. Inspectthe insulator plate for cracks or distortion,
which can occur if the screws are improperlyinstalled. Replace if defective.
2. If the engine stalls when testing the reversesafety switch, check the seat safety switch bydisconnecting both yellow wires on the switch.
With the engine running and the shift lever inneutral, release the clutch/brake pedal. If theengine continues to run, the problem is withthe insulator plate on the seat safety switch.Inspect in the same manner as the reversesafety switch. Replace if defective. See Figure3-34.
Figure 3-34.
Problem: Your unit has an electric PTO and the bladesdo not engage when activating the PTO switch.
1. Check for voltage at the PTO connector withthe PTO switch in the on position.
If there is voltage, adjust the PTO clutch orreplace it as needed.
2. If there is no voltage, check for voltage at thered wire at the PTO switch. If no voltage, checkfor voltage at the ignition switch. See Figure 3-35.
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Figure 3-35.
3. If there is voltage at the red wire at the PTO,switch the PTO to the start position and checkfor voltage at the blue and brown wire. If thereis no voltage at either, replace the PTO switch.See Figure 3-36.
Figure 3-36.
Problem: The engine stalls when engagingblade or the blades do not engage when goinginto the run position on units with PTO’s.
Check both the reverse safety switch and seatsafety switch for grounding out conditions.
NOTE
Wires must not come into contact with the unitwhen checking these connections.
1. Disconnect the yellow wire on the reversesafety switch. With the engine running, engagethe cutting deck.
If the blades engage without stalling theengine, the screws on the reverse safetyswitch are grounding out against the support
bracket or panel. Correct by removing thescrews that hold the reverse safety switch tothe bracket or panel. Inspect the insulator platefor cracks or distortion, which can occur if thescrews are improperly installed. Replace ifdefective.
If the engine stalls, reconnect yellow wires andproceed to the next step.
2. Check the seat safety switch by disconnectingboth yellow wires or the harness from theswitch. See Figure 3-37.
Figure 3-37.
With the engine running, engage the cuttingdeck. If the engine continues to run with theblades engaged, the problem is with the insu-lator plate on the seat safety switch. Inspect inthe same manner as the reverse safety switch.Replace if defective.
Problem: PTO starts but disengages when theswitch is moved to the run position.
1. Check the wiring at the PTO switch. See Fig-ure 3-38.
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If correct, check voltage at PTO when bladestops turning. If voltage is present and bladesare not turning, check the clutch air gap andadjust, retest, and replace the clutch if the testfails. See Figure 3-39.
Figure 3-39.
2. If voltage is not present, disconnect the wiresfrom the seat safety switch and the reversesafety switch.
Operate the PTO. If it remains running, checkthe safety switches for shorts or broken insula-tor plates.
3. If the PTO doesn’t operate, test the relays asfollows:
a. Test for voltage on relay one at the whitewire with the PTO switch in the start posi-tion. If there is no voltage, replace relayone. See Figure 3-40.
Figure 3-40.
b. If voltage is present in relay one, check forvoltage on the red wire of relay two.
c. If voltage is present, replace relay two.
4. If no voltage is present at relay two, check forvoltage at the red wire on the ignition switch. Ifthere is no voltage, replace the ignition switch.See Figure 3-41.
Figure 3-41.
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EVALUATING ELECTRIC CLUTCHES
This section will cover how to evaluate electricclutches. You will need a multi meter to per-form these tests.
1. To measure the clutch coil resistance, turn offthe engine and the PTO switch.
a. Disconnect the clutch wire connection.
b. Set the meter to check ohms.
c. Connect the meter lead wires to the wiresin the clutch connector. See Figure 3-42.
Figure 3-42.
(1) If the meter reads below 2.40 ohms orabove 3.40 ohms, the clutch has failedand needs to be replaced.
(2) If the meter reads between 2.40 and3.40 ohms, proceed to measuringclutch current draw.
2. Set the meter to check amps using the 10 ampscale.
a. Connect one meter lead wire to one wire inthe clutch connector and the other leadwire to the corresponding wire in the mat-ing connector.
b. Connect a short wire to the second wire inboth connectors. See Figure 3-43.
Figure 3-43.
c. Turn the PTO switch on.
3. If the meter reads below 3.5 amps, the prob-lem would be in the electrical system leading tothe clutch such as the battery, a relay, or aswitch.
4. If the meter reads 3.5 amps or above, proceedto checking the air gap.
a. Turn off the PTO.
b. Locate the three windows or notcheswhere the air gap is checked.
c. Check the gap at three locations using afeeler gauge.
d. The factory air gap setting is .010 to .025inch. See Figure 3-44.
Figure 3-44.
e. If the gap is incorrect, use a .017 feelergauge and adjust the gap by tightening or
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loosening the three nuts on the clutch. SeeFigure 3-45.
Figure 3-45.
5. The electric clutch initially needs to be bur-nished before it is used by the owner.
It is not done at the factory and is the responsi-bility of the dealer or the customer.
a. To properly burnish the clutch, run theengine at 50 percent throttle.
b. Engage and disengage the clutch 5 times,ten seconds on and ten seconds off.
c. Increase to 75 percent throttle.
d. Engage and disengage the clutch 5 moretimes, ten seconds on and ten seconds off.
6. If you have a unit with an electric clutch thatoperates sporadically, check all wiring aroundthe steering column going to the dash for fray-ing and shorts.
a. Check the relays for proper connections.Newer models have in line relays to mini-mize vibration and reduce failure.
b. You can remove the relays from the chas-sis of older models and tape them directlyto the wiring harness.
c. Check the PTO switch for proper connec-tions. The red and blue wires might bereversed. The blue wire should be on topwith the red wire directly below it. Thebrown wire should be on the opposite side.
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