cat 3126 eletric diagrama
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©2001 C
aterpillarAll R
ights Reserved
Printed in U.S.A.
SENR
9628N
ovember 2001
3126 Truck E
ngineE
lectrical System
1BW
1-UP
TOP VIEW
LEFT SIDE VIEW
ECMGroundStrap
Electronic ControlModule (ECM)
Electronic ControlModule (ECM)
ECM EngineHarnessConnectorJ2/P2
ECM VehicleHarnessConnectorJ1/P1
InjectorHarnessGrommet
TimingCalibrationProbeConnectorJ24/P24
Timing CalibrationProbe ConnectorJ24/P24
InjectorHarnessGrommet
InjectionActuationPressureSensor
GroundStud
InjectionActuationPressureSensor
Intake ManifoldAir TemperatureSensor
UnitInjectorCylinder #6
654321
Intake ManifoldAir TemperatureSensor
Engine OilTemperatureSensor
Engine OilTemperatureSensor
HighPressurePump
HighPressurePump
BoostPressureSensor
CoolantTemperatureSensor
Injection ActuationPressure ControlValve (IAPCV)
Injection ActuationPressure ControlValve (IAPCV)
TopSpeed/TimingSensor
BottomSpeed/TimingSensor
*
*
Inlet Air HeaterLamp ConnectorP40
Inlet AirHeater
INPUT SIGNAL WIRES TO ECM
OUTPUT SIGNAL WIRES FROM ECM
SENSOR SUPPLY VOLTAGE
(+) BATTERY SUPPLY WIRES
SIGNAL PLUS
(-) BATTERY / SENSOR RETURN
SIGNAL MINUS
P2 J2
J51 P51
CBA
ENGINE OILTEMPERATURE
SENSOR
E795-YL993-BR997-OR
ENGINE OIL TEMPSENSOR COMMON
+5V
WHBKOR
INTAKE MANF AIR TEMPSENSOR COMMON
+5V
J10 P10
C967-BU993-BR997-OR
INTAKE MANIFOLDAIR TEMPERATURE
SENSOR ABC
WHBKOR
N/O
RELAYJ37
J36 P36
J24 P24J34 P34
J33 P33
J32 P32
J31 P31
J30 P30
J29 P29
BOOST PRESSURESENSOR COMMON
+5V
BOOSTPRESSURE
SENSOR
INJECTIONACTUATIONPRESSURE
SENSOR
CYLNO.1
CYLNO.2
CYLNO.3
CYLNO.4
CYLNO.5
A706-GYA726-OR
A705-BUA725-YL
A704-GNA724-WH
CBA
A746-PK993-BR997-OR
12
P3 J3
INJECTION ACTUATION
TIMING CALIBRATIONPROBE CONNECTOR
PRESSURE CONTROL VALVEAB
INLET AIRHEATER
INLET AIRHEATERGROUND STRAP
INLET AIRHEATER
E965-BUE966-YL
CYLNO.6
E963-BKE964-WH
TO ENGINE CYL HEAD(NOT CYL HEAD GND STUD)
TO +BATTERY
21
A703-BRA723-OR
A702-PUA722-YL
BA
BA
AB
AB
AB
AB
AB
WHBKOR
INJECTOR HARNESS GROMMET
D796-ORD812-RD
469468
GNYLOR
TO ECM
MOUNTING
BOLT
D797-PKD798-BK
65
12111817222128273433
INJECTOR 1INJECTOR COMMON 1INJECTOR 2INJECTOR COMMON 2INJECTOR 3INJECTOR COMMON 3INJECTOR 4INJECTOR COMMON 4INJECTOR 5INJECTOR COMMON 5INJECTOR 6INJECTOR COMMON 6VEHICLE SPEED OUT+VEH SP IN+/TDC PROBE+VEH SP IN-/TDC PROBE-VEHICLE SPEED OUT-INJ ACTUATION PRESS. CONT VALVEIAP CONT VALVE COMMON
ENG SP/TMG #1-ENG SP/TMG #1+
ECM GND STRAP
ELECTRONIC CONTROL MODULE (ECM)
ELECTRONIC CONTROL MODULE (ECM)
ENG SP/TMG #2-ENG SP/TMG #2+BOOST PRESSUREINJ ACTUATION PRESS.COOLANT TEMPINTAKE MANF AIR TEMPOIL TEMP
SENSOR COMMON+5V
INLET AIR HEATER
372925153
2324142
327
1626303638203531
40394
101913189
A
INJ ACTUATION PRESS.SENSOR COMMON
+5V
GNYLOR
B
TOP SPEED/TIMING SENSOR ENGINE SPEED / TIMING -ENGINE SPEED / TIMING +
ENGINE SPEED / TIMING -ENGINE SPEED / TIMING +
P35 J35
J9 P9
A701-GYA721-WH
J4 P4
B
D841-GN993-BR997-ORA
BC
A
A701-GYA721-WHA702-PUA722-YLA703-BRA723-ORA704-GNA724-WHA705-BUA725-YLA706-GYA726-ORD784-BUD810-PUD811-YLD785-GND797-PKD798-BK
E963-BKE964-WH
COOLANT TEMPSENSOR COMMON
+5V
995-BU993-BR997-OR
COOLANTTEMPERATURE
SENSOR ABC
D812-RDD796-OR
D812-RD
D796-OR
BOTTOM SPEED/TIMING SENSOR
P40
APCCONNECTED TOLAV HARNESS ORAPC HARNESS
LAV
P37
J21 P21
E965-BUE966-YLA746-PKD841-GN995-BU
C967-BUE795-YL
993-BR997-OR
D796-OR
AB
J1
P6 J1
P1J2
P1 J1
P1J1
469468
BA
35 +8V30 MULTI-FUNCTION SENSOR COMMON37 THROTTLE POSITION
EXHAUST BRAKE40XMSN NEUTRAL SW38SERVICE BRAKE SW #114
2 FAST IDLE ENABLE SW29 SENSOR COMMON
CHECK ENGINE LAMP227 ATA DATA LINK+ (J1587)1 ATA DATA LINK- (J1587)
VEHICLE SPEED IN+185 -BATTERY
28 +BATTERY4 -BATTERY6 +BATTERY
3 NOT USED8 NOT USED9 NOT USED
11 NOT USED10 NOT USED
12 NOT USED13 NOT USED15
FROM (J1)ELECTRONIC
CONTROL MODULE(ENGINE)
FROM (J1)ELECTRONIC
CONTROL MODULE(ENGINE)
NOT USED16 NOT USED17 NOT USED19 NOT USED20 NOT USED21 NOT USED23 NOT USED24 NOT USED25 NOT USED26 NOT USED27 NOT USED31 NOT USED32 NOT USED33 NOT USED34 NOT USED36 NOT USED39 NOT USED
+8VMULTI-FUNCTION SENSOR COMMON
LAV INTERFACE HARNESS
THROTTLE POSITIONEXHAUST BRAKEXMSN NEUTRAL SWSERVICE BRAKE SW #1FAST IDLE ENABLE SWSENSOR COMMONCHECK ENGINE LAMPATA DATA LINK+ (J1587)ATA DATA LINK- (J1587)VEHICLE SPEED IN+-BATTERY+BATTERY-BATTERY+BATTERY
570 35571
469468
30572 37573 40574 38
1457589 2577 29
22578586 7585 1
18579581 5580 28581 4580 6
KLMNPRSTUVWXYZEAAFBCD
TO VEHICLECOMPONENTS
TOPOWER PACKINTERFACE
ENGINEBULKHEAD
DEFGHJ
KLMNPRSTUVWXYZEAAFBCDDEFGHJ
389
1110
12131516171920212324252627313233343639
+8VMULTI-FUNCTION SENSOR COMMON
APC INTERFACE HARNESS
THROTTLE POSITIONEXHAUST BRAKEXMSN NEUTRAL SWSERVICE BRAKE SW #1FAST IDLE ENABLE SWSENSOR COMMONCHECK ENGINE LAMPATA DATA LINK+ (J1587)ATA DATA LINK- (J1587)VEHICLE SPEED IN+-BATTERY+BATTERY-BATTERY+BATTERY
570 35571 30572 37573 40574 38
14575576 2577 29
22578142 7151 1
18579581 5580 28581 4580 6
KLMNPRSTUVWXYZeAafbcD
TO VEHICLECOMPONENTS
TOPOWER PACKINTERFACE
POWER PACKBULKHEAD
d
BC
EFGHJ
KLMNPRSTUVWXYZeAafbcDd
BC
EFGHJ
389
1110
12131516171920212324252627313233343639
BC
BC
469468
RIGHT SIDE VIEW
Inlet AirHeaterRelay
Inlet AirHeaterGroundStrap
Inlet AirHeater
AB
CONNECTED TOLAV HARNESS ORAPC HARNESS
SENR9525-008 Page, JVD
1999 Caterpillar
All Rights Reserved
Printed in U.S.A.©
SENR9525
November 1999
3126B Truck Engine
Electrical System
6PZ1-UP
7JZ1-UP
Engine Pressure Sensor Open or Short Circuit Test
Connect Electronic Service Tool to Cab Data Linkand check for ACTIVE 5 Volt Sensor Supply Code.
Check for ACTIVE Engine Pressure Sensor OPEN or SHORTCircuit Code. If the code is not ACTIVE and the Engine is not running
properly, refer to Troubleshooting Without A Diagnostic Code.
ACTIVESupply Code
Refer to +5VoltPressure Sensor
Supply Voltage
Circuit Test
NO ACTIVESupply Codes
ACTIVEOpen or ShortCircuit Code
Turn the ignition key ON, engine OFF. Disconnect theSensor Connector with the ACTIVE Short CircuitCode in order to create an Open Circuit condition.
Measure Sensor Supply Voltagewith multimeter. Reading should be
within 4.5 to 5.5 VDC range.
Active SHORTCircuit Code
Active OPENCircuit Code
NOTOK Refer to Inspecting
Electrical ConnectorsCheck Electrical Connectors and Wiring.
If a Short Circuit code was Active before the sensorwas disconnected and an Open Circuit code became
Active after the sensor was disconnected thenthoroughly inspect the connector for signs of moisture.Inspect the seals and connect the sensor. If the codereappears, the sensor or pigtail harness is the problem.Temporarily connect a new sensor but do not install itinto the engine. If the code is no longer Active with the
new sensor connected, replace the old sensor.
Code ChangesTo OPEN Circuit
SHORT CircuitCode Remains
Refer to +5Volt
Engine Pressure
Sensor Supply
Voltage Circuit
Test
NOTOK
Supply OK
Install a short circuit between terminal-B andterminal-C of the Sensor Connector and check
for an ACTIVE Short Circuit code.
OPEN Circuit CodeActive with jumper
If a SHORT Circuit Code appears,temporarily connect the suspect
sensor. If an OPEN Circuit code returns,replace the sensor and verify thediagnostic code does not return.
SHORT Circuit CodeActive with jumper
Disconnect the ECM Connector J2/P2 and check for Activediagnostic codes. The OPEN Circuit code should be Active withthe harness disconnected. Install a jumper (short) between theECM Connector J2 signal terminal and terminal-3. A SHORTCircuit code should be Active with the jumper installed.
If the OPEN Circuit code is NOT Active with the harnessdisconnected, or the SHORT Circuit code is NOT Activewith the jumper (short) installed, temporarily install atest ECM. If the test ECM resolves the problem,
install the old and verify problem returns. If the test ECMworks and the original ECM does not, replace the ECM.
NOT OK
Remove the sensor signal wire from ECM connectorP2 and the sensor connector. Bypass the signal wiring byconnecting a jumper wire directly from ECM connector P2to the sensor connector signal terminal. If the DiagnosticCode disappears with the bypass wire installed, repair orreplace the harness. Otherwise, restart the test procedure.
OK
Engine Temperature Sensor Open or Short Circuit Test
Connect an Electronic Service Tool and check for an ACTIVEEngine Temperature Sensor OPEN or SHORT Circuit Code.If the code is not ACTIVE and the Engine is not running
properly, refer to Troubleshooting Without A Diagnostic Code.
ACTIVEOpen or ShortCircuit Code
With the ignition key ON and engine OFF, Disconnect theSensor Connector with the ACTIVE Short Circuit Code
in order to create an Open Circuit condition.
Active SHORTCircuit Code
Active OPENCircuit Code
NOTOK Refer to Inspecting
Electrical ConnectorsCheck Electrical Connectors and Wiring.
If a Short Circuit code was Active before the sensorwas disconnected and an Open Circuit code became
Active after the sensor was disconnected thenthoroughly inspect the connector for signs of moisture.Inspect the seals and connect the sensor. If the codereappears, the sensor is the problem.Temporarily connect a new sensor but do not install itinto the engine. If the code is no longer Active with the
new sensor connected, replace the old sensor.
Code ChangesTo OPEN Circuit
SHORT CircuitCode Remains
With the ignition key On and engine OFF, Install a shortcircuit between terminal-1 and terminal-2 of the SensorConnector and check for an ACTIVE Short Circuit code.
OPEN Circuit CodeActive with jumper
If a SHORT Circuit Code appears,temporarily connect the suspect
sensor. If an OPEN Circuit code returns,replace the sensor and verify thediagnostic code does not return.
SHORT Circuit CodeActive with jumper
Disconnect the ECM Connector J2/P2 and check for Activediagnostic codes. The OPEN Circuit code should be Active withthe harness disconnected. Install a jumper (short) between theECM Connector J2 signal terminal and terminal-18. A SHORT
Circuit code should be Active with the jumper installed.
If the OPEN Circuit code is NOT Active with the harnessdisconnected, or the SHORT Circuit code is NOT Activewith the jumper (short) installed, temporarily install atest ECM. If the test ECM resolves the problem,
install the old and verify problem returns. If the test ECMworks and the original ECM does not, replace the ECM.
NOT OK
Remove the sensor signal wire from ECM connectorP2 and the sensor connector. Bypass the signal wiring byconnecting a wire directly from ECM connector P2 tothe sensor connector signal terminal. If the DiagnosticCode disappears with the bypass wire installed, repair orreplace the harness. Otherwise, restart the test procedure.
OK
Electronic Service Tool Will NotCommunicate with the ECM
Try to start the Engine.
Connect another Service Tool to theECM, but use the same Service ToolCables as in the previous step.
Connect Electronic Service Tool to the Cab data link,turn ignition key switch ON, engine OFF. Attemptto establish communications with the ECM.
Ensure after-market engine protectiondevices (not installed by Caterpillar) arenot active, preventing the ECM or IgnitionKey Switch from receiving battery power.
Connect the Service Tool using acompletely different set of Service
Tool cables.
Either the vehicle wiring or anotherdevice on the vehicle is causing the
communication problem.
Connect a test ECM. Turn the Ignition Key ON,engine OFF. If the new ECM communicates andthe old ECM does not, reconnect the old ECMand verify the problem returns. If the new ECM
communicates and the old ECM does not, replacethe ECM. If the new ECM does not communicate,there is a problem with the cables or the battery.
A new ECM has an unprogrammedPersonality Module. The engine will not startor communicate until the Personality Module
in the ECM is Flash Programmed.
Disconnect ECM Connector P1 fromthe ECM. Use the Service Tool BypassHarness as indicated in the Ignition
Key Switch Circuit Test.
Doesnot start
Engine starts, but
with the Service Tool
ECM does not
communicate
No Communications
ECM CommunicatesECM does not communicate
No Communications
No Communications
Engine Cranks, But Will Not Start
Does not crank,
refer to engine
will not crank.
RepairServiceTool
Refer to the
Ignition
Keyswitch
Circuit Test
Referto the
ECM
Memory
Test
RepairCables
ECM and ServiceTool Communicate
OK
OK
OK
Not a New ECM
NOT
OK
NOT
OK
NOT
OK
OKCheck ECM power, ground, and keyswitchconnections with the ignition key switch ON.Battery voltage at ECM Connector J1/P1
terminal-52, 53 and 70, to terminal-65 and 67should be 11.0 -13.5 VDC for a 12 Volt
system and 22.0 - 27.0 for a 24 Volt system.
Check the Ignition Key Switch status on the ServiceTool. With the Ignition Key Switch ON, the status
should display ON. If the status displays OFF, checkfor voltage from the battery. Battery voltage at
ECM Connector J1/P1 terminal-70 to terminal-65and 67 should be 11.0 -13.5 VDC for a 12 Volt system
and 22.0 - 27.0 for a 24 Volt system.
If the has been
, connect and check for anactive 252-11 Incorrect Engine Software.
Personality Module recently
replaced/updated
Observe from Electronic Service
Tool the engine. An rpm value
should be displayed on the Service Tool.
engine rpm
while cranking
If the Truck is equipped with a , ensure
is not . Turn theIgnition Key Switch ON, engine OFF, theCAT ID will indicate Theft Deterrent Active.
CAT ID
Theft Deterrent Active
Monitor the while cranking - if
is present there may be a fuelsupply or quality problem. Check fuel
pressure, priming, and filters.
exhaust stack
no smoke
Check for combustion problems,mechanical problems or extreme temperatures.
Refer
to the
Engine
Speed/Timing
Circuit Test
OK
OK
OK
OK
OK
NOT
OK
NOT
OK
Referto the
Ignition
Keyswitch
Circuit Test
Referto the
ECM
Memory
Test
NOTE: Refer to the Electronic Troubleshooting Guide for detailed information.
NOTE: Refer to the Electronic Troubleshooting Guide for detailed information.
NOTE: Refer to the Electronic Troubleshooting Guide for detailed information. NOTE: Refer to the Electronic Troubleshooting Guide for detailed information.
SENR9525-00
8Page,Color2,JVD
INPUT SIGNAL WIRES TO ECM
OUTPUT SIGNAL WIRES FROM ECM
SENSOR SUPPLY VOLTAGE
(+) BATTERY SUPPLY WIRES
SIGNAL PLUS
(-) BATTERY / SENSOR RETURN
SIGNAL MINUS
A
BINJECTION ACTUATION
PRESSURE CONTROL VALVEJ500 P500
J400 P400
B
A
TOP CAMSHAFT SPEED/TIMING-
TOP CAMSHAFT SPEED/TIMING+
BOTTOM CAMSHAFT SPEED/TIMING-
BOTTOM CAMSHAFT SPEED/TIMING+
E963-BK
E964-WH
E965-BU
E966-YL
49
48
13
19
20
21
28
29
3059
58
31
43
51
22
23
56
57
65
66
69
8
G856-WH
G857-YL
A
B
TOP CAMSHAFT ENGINE
SPEED/TIMING SENSOR
TOP CAMSHAFT SPEED/TIMING-
TOP CAMSHAFT SPEED/TIMING+
J401 P401
J402 P402
B
A
BOTTOM CAMSHAFT SPEED/TIMING-
BOTTOM CAMSHAFT SPEED/TIMING+
BOTTOM CAMSHAFT ENGINE
SPEED/TIMING SENSOR
1
2ENGINE COOLANT
TEMPERATURE
995-BU
G833-PK
J100 P100
ENGINE COOLANT TEMPERATURE
ENGINE TEMPERATURE SENSOR COMMON
ENGINE INTAKE MANIFOLD AIR TEMPERATURE
ENGINE TEMPERATURE SENSOR COMMON
J103 P103
C967-BU
G833-PK
ENGINE INTAKE
MANIFOLD AIR
TEMPERATURE
1
2
995-BU
C967-BU
G833-PK
C
B
A
G849-BR
G829-GN
G828-WH
A746-PK
G849-BR
A747-GY
G829-GN
G828-WH
P204 J204
ENGINE OIL PRESSURE SENSOR
ENGINE OIL PRESSURE SENSOR COMMON
ENGINE OIL PRESSURE SENSOR +5V
ENGINE ATMOSPHERIC
PRESSURE
NOTE A
GN
YL
OR
ENGINE INJECTION
ACTUATION
PRESSURE
ENGINE INJECTION ACTUATION PRESS
ENGINE PRESSURE SENSOR COMMON
ENGINE PRESSURE SENSOR +5V
GN
YL
OR
P201 J201
994-GY
G827-BU
G826-BRA
B
C
J200 P200
A746-PK
G829-GN
G828-WHA
B
C
SENSOR
ENGINE BOOST
PRESSURE
ENGINE BOOST PRESSURE
ENGINE PRESSURE SENSOR COMMON
ENGINE PRESSURE SENSOR +5V
GN
YL
0R
COMPONENTS ARE SHOWN WITH THE KEY OFF
UNLESS OTHERWISE SPECIFIED:
ALL WIRES TO BE 18 AWG OR LARGER SAE J1560 TYPE TXL
OR EQUIVALENT. FOR TWISTED PAIR SPECIFICATION SEE
SAE J1708
INTAKE AIR HEATER RELAY
ENGINE COOLANT TEMPERATURE
ENGINE INTAKE MANIFOLD AIR TEMPERATURE
ENGINE OIL TEMPERATURE
ENGINE TEMPERATURE SENSOR COMMON
ENGINE ATMOSPHERIC PRESSURE
ENGINE PRESSURE SENSOR COMMON
ENGINE PRESSURE SENSOR +5V
IAP CONTROL VALVE
IAP CONTROL VALVE COMMON
ENGINE BOOST PRESSURE
ENGINE INJECTION ACTUATION PRESSURE
P1 J1
ECM GROUND STRAP
G854-PK
G855-PU
TO ECMMOUNTINGBOLT
ENGINE HARNESS CONNECTOR
VEHICLE HARNESS CONNECTOR
C987-RD
G850-BU
P648
TO CONNECTOR J648
A
B
K995-OR
G850-BU
C987-RD
1
2
ENGINE TIMING CALIBRATION PROBE+
ENGINE TIMING CALIBRATION PROBE-
TO INTAKE AIR HEATER
CIRCUIT FUSIBLE PROTECTION
TO ENGINE CYLINDER HEAD
(NOT CYLINDER HEAD GROUND STUD)
INTAKE AIR
HEATER
G850-BU
P2 J2
ENGINE TIMING CALIBRATION PROBE+
ENGINE TIMING CALIBRATION PROBE-
J501 P501
N/O
RELAY
32
35
33
34
26
18
10
11
12
15
16
17
24
25
41
42
50
52
53
60
9
40
27
6
7
14
3
2
B
A
INJECTOR
CYLINDER
NO.5
1
63
64
4
5
61
62
70
INJECTOR
CYLINDER
NO.6
B
A
J306 P306J305 P305J304 P304J303 P303J302 P302
L984-OR
B
A
INJECTOR
CYLINDER
NO.4
INTAKE MANIFOLD GROMMET
J301 P301
INJECTOR
CYLINDER
NO.1
A704-GN
B
A
A705-BU
A703-BR
A702-PU
A701-GY
L985-YL
L984-OR
A706-GY
L985-YL
L983-WH
L983-WH
INJECTOR
CYLINDER
NO.3
B
A
B
A
INJECTOR
CYLINDER
NO.2
P300 J300
L983-WH
L984-OR
L985-YL
A706-GY
A705-BU
A704-GN
A703-BR
A702-PU
A701-GY
INJECTOR COMMON CYLINDERS 1 & 2
INJECTOR COMMON CYLINDERS 3 & 4
INJECTOR COMMON CYLINDERS 5 & 6
INJECTOR CYLINDER 6
INJECTOR CYLINDER 5
INJECTOR CYLINDER 4
INJECTOR CYLINDER 3
INJECTOR CYLINDER 2
INJECTOR CYLINDER 1
44
45
46
55
54
39
38
37
36
47
67
68
12
11
10
9
8
7
6
5
4
3
2
1
3126B ENGINE HARNESS WIRING DIAGRAM
NOTE A
EXHAUST BRAKE
ON/OFF SWITCH
FLYBACK
DIODEEXHAUST BRAKE
SOLENOID
TO ALLISON AT/MT SHIFT
MODULATOR FOR MECHANICAL
TRANSMISSION
COOLING FAN SOLENOID
NOTE A
INTAKE AIR
HEATER LAMPTO CONNECTOR P648
J648
100AWITH 130A PEAK AT 11V
C987-RD
TO INTAKE AIR
HEATER RELAY
(CONTACT SIDE)
SPEEDOMETER
NOTE A
NOTE A
SENSOR ACCELERATOR
PEDAL POSITION
BK
RD
WH
J403 P403
ACCELERATOR PEDAL SENSOR/SWITCH SENSOR COMMON
+8 V
ACCELERATOR PEDAL POSITION
B
A
C
L901-GY
C977-BU
G879-OR
H795-PK
H795-PK
A/C HIGH PRESS. SWITCH
N/C
E971-GN
450-YL
451-BR
SIGNAL+
SIGNAL-
NOTE A
TACHOMETER
NOTE A
INPUT SENSOR COMMON #1
CLUTCH PEDAL POSITION SWITCH
+5V
E793-BU
E794-YL
INPUT #12
INPUT #11
INPUT #7
ENGINE COOLANT LEVEL NORMAL
ENGINE COOLANT LEVEL LOW
VEHICLE SPEED IN POSITIVE
VEHICLE SPEED IN NEGATIVE
INPUT #8
20A
14 AWG GXL
14 AWG GXL
14 AWG GXL
14 AWG GXL
AP SENSOR/SWITCH SENSOR COMMON
+8V
ACCELERATOR PEDAL POSITION
OUTPUT #5
18
22
23
2
46
49
54
PASSIVE MAGNETIC
VEHICLE SPEED
SENSOR
G808-BU
G809-GN
H795-PK
H795-PK
SET/RESUME
ENGINE
BLOCK
62
24
409-OR
E971-GN
E793-BU
E794-YL
A249-BK
K990-GN
K900-YL
J906-BR
COMPONENTS WITHIN THIS AREAARE CATERPILLAR PROVIDED
CLUTCH PEDAL POSITION N/C
SERVICE BRAKE PEDAL POSITION N/C
(PEDAL RELEASED POSITION)
NOTE A
CRUISE CONT ON/OFF
CHECK ENGINE LAMP
WARNING LAMP
+BAT.
-BAT.
J1587 DATA LINK NEGATIVE
J1587 DATA LINK POSITIVE
TO J1939 DATA LINK CONNECTOR
TO J1939 DATA LINK CONNECTOR
TO J1939 DATA LINK CONNECTOR
1
2
D
H795-PK
E
C
F
CAB DIAGNOSTIC CONNECTOR
B
A
5
4
66
11
41
69
32
33
68
VEHICLE HARNESS CONNECTOR
P2 J2
H795-PK
C985-BU
C986-BR
G837-YL
B
A
659-PK
L994-YL
K998-BU
G880-PK
CIRCUITS WITHIN THIS AREAARE RECOMMENDATIONS
SERVICE BRAKE PEDAL POSITION SWITCH
INPUT #5
INPUT #13
INPUT #6
SIGNAL-
SIGNAL+
+BAT.
NOTE A
(TRANSMISSION IN GEAR)
START
ONOFF
NOTE A
45
55
47
64
6
C992-PU
G842-GY
G882-WH
G843-OR
K995-OR
C987-RD
C974-PU
C973-GN
993-BR
F713-OR
STARTER
MOTOR
(12V)
FLYBACK
DIODE
NOTE A
CRUISE CONTROL ON/OFF SWITCH
INPUT #3
INPUT #4
59
60
7
BATTERY 2
C975-WH
K982-YL
G841-GN
N/O
RELAY
H795-PK
C985-BU
C986-BR
SET
RESUME
INPUT #1
INPUT #2
INPUT #18
OUTPUT #8
C978-BR
C979-OR
C977-BU
C992-PU
C975-WH
35
44
56
58
40
21
C978-BR
C979-OR
K999-GN
K980-PK
L902-GN
G840-PU
C973-GN
C974-PU
KEY SWITCH
659-PK
GROUND
L994-YL
ALTERNATOR
- 12V+- 12V+ +
P1 J1
12V-
BATTERY 3 BATTERY 1
G808-BU
G809-GN
G845-PU
ENGINE HARNESS CONNECTOR
J1587 DATA LINK NEGATIVE
J1587 DATA LINK POSITIVE
J1939 DATA LINK SHIELD
J1939 DATA LINK NEGATIVE
J1939 DATA LINK POSITIVE
IGNITION KEY SWITCH
UNSWITCHED +BATTERY
UNSWITCHED +BATTERY
-BATTERY
-BATTERY
OUTPUT #6
OUTPUT #7
52
53
65
67
19
20
51
101-RD
101-RD
229-BK
229-BK
G838-BR
G839-BU
9
8
42
34
50
1
14
70
25
TACHOMETER POSITIVE
TACHOMETER NEGATIVE
38
39
57
43
G844-PK
C983-WH
C984-YL
450-YL
451-BR
H795-PK
FAST IDLE ENABLE SWITCH
L902-GNN/O MOMENTARY SWITCH
NOTE A
NOTE A
NOTE A
G880-PK
FAST IDLE
ENABLED LAMP
N/O MOMENTARY SWITCH
G844-PK
SPEEDOMETER POSITIVE
SPEEDOMETER NEGATIVE
INPUT SENSOR COMMON #2
INPUT #14
36
37
27
26
3
17
DIAGNOSTIC ENABLE SWITCH
H795-PK
(PEDAL RELEASED POSITION)+BAT.
29
28
30
31
48
61
10
12
13
15
16
63
NOTE AG882-WH
SERVICE BRAKE PEDAL POSITION #2 N/O
(PEDAL RELEASED POSITION)
WARNING LAMP
CHECK ENGINE LAMP
OUTPUT #1
OUTPUT #9
TRANSMISSION NEUTRAL N/O
409-OR
OUTPUT #2
OUTPUT #3
OUTPUT #4
E718-PK
E991-GY
G836-WH
3126B VEHICLE HARNESS WIRING DIAGRAM
G846-YL
ENGINE OIL TEMPERATURE
ENGINE TEMPERATURE SENSOR COMMON
J101 P101
G846-YL
G833-PK
1
2
SENSOR
SENSOR
SENSOR
ENGINE OIL
TEMPERATURE
SENSOR
SENSOR
Engine Harness Connector P2
ECM AMP Connectors
ECM Side
BB
AA
C C
11 22
1 2 3 4 5 66 5 4 3 2 1
12 11 10 9 8 7 7 8 9 10 11 12
Harness Side
23
31
47
57
14
24
40
48
58 59 60 61 62 63 65 66 67 68 69 70
1 2 3 4 5 6 8 9 10 11 12 13
36
>PEI<
1
14
24
32
40
48
58
13
23
31
39
47
57
70
Harness Side
23
31
47
57
14
24
40
48
58 59 60 61 62 63 65 66 67 68 69 70
1 2 3 4 5 6 8 9 10 11 12 13
36
>PEI<
Vehicle Harness Connector P1ECM Side
1
14
24
32
40
48
58
13
23
31
39
47
57
70
Deutsch DT Connector Receptacle Deutsch DT Connector Plug
Pressure
Sensor
Connectors
Temperature
Sensor
Connectors
Injector
Harness
Connectors
NOTE A: A DASHED LINE SPECIFIES AN OPTIONAL FEATURE, NOT AVAILABLE ON ALL SYSTEMS.
NOTE A: A DASHED LINE SPECIFIES AN OPTIONAL FEATURE, NOT AVAIL ABLE ON ALL SYSTEMS.
NOTE A
NOTE A
ENGINE ATMOSPHERIC PRESSURE
ENGINE PRESSURE SENSOR COMMON
ENGINE PRESSURE SENSOR +5V
GN
YL
OR
P203 J203
A747-GY
G829-GN
G828-WHA
B
C
994-GY ENGINE OIL PRESSURE SENSOR
ENGINE OIL
PRESSURE
NOTE ASENSOR
G827-BU
G826-BR
ENGINE OIL PRESSURE SENSOR COMMON
ENGINE OIL PRESSURE SENSOR +5V
PID-FMI Description Flash
Codes
PID-FMI Description Flash
Codes
1-11 Cylinder 1 Fault 72 102-07 Excessive Boost Pressure 25
2-11 Cylinder 2 Fault 72 105-03 Inlet Manifold Air Temp Sensor Open Circuit 38
3-11 Cylinder 3 Fault 73 105-04 Inlet Manifold Air Temp Sensor Short Circuit 38
4-11 Cylinder 4 Fault 73 108-03 Atmospheric Press Sensor Open Circuit 26
5-11 Cylinder 5 Fault 74 108-04 Atmospheric Press Sensor Short Circuit 26
6-11 Cylinder 6 Fault 74 110-00 High Coolant Temp Warning 61
22-13 Check Timing Sensor Calibration 42 110-03 Coolant Temp Sensor Open Circuit 27
30-08 Invalid PTO Throttle Signal 29 110-04 Coolant Temp Sensor Short Circuit 27
30-13 PTO Throttle Sensor Calibration 29 110-11 Very High Coolant Temp 61
41-03 8 Volt Supply Above Normal 21 111-01 Low Coolant Level Warning 62
41-04 8 Volt Supply Below Normal 21 111-02 Coolant Level Sensor Fault 12
42-11 Injection Actuation Press
Control Valve Driver Fault
18 111-11 Very Low Coolant Level 62
43-02 Ignition Key Switch Fault 71 164-00 Injection Actuation Press Out of Range 17
64-02 Loss of Engine RPM Signal on Engine
Speed and Timing Sensor Number 2
34 164-02 Injection Actuation Press Sensor Erratic 15
64-11 No Pattern on Engine Speed
and Timing Sensor Number 2
34 164-03 Injection Actuation Press Open Circuit 15
70-05 Inlet Air Heater Open Circuit 49 164-04 Injection Actuation Press Short Circuit 15
70-06 Inlet Air Heater Short Circuit 49 164-11 Injection Actuation Press System 39
71-00 Idle Shutdown Override 01 168-02 Intermittent Battery Power to the ECM 51
71-01 Idle Shutdown Occurrence 47 175-03 Oil Temp Sensor Open Circuit 24
71-14 PTO Shutdown Occurrence 47 175-04 Oil Temp Sensor Short Circuit 24
84-00 Vehicle Overspeed Warning 41 190-00 Engine Overspeed Warning 35
84-01 Loss of Vehicle Speed Signal 31 190-02 Loss of RPM Signal on Engine Speed
and Timing Sensor Number 1
34
84-02 Invalid Vehicle Speed Signal 36 190-11 No Pattern on Engine Speed
and Timing Sensor Number 1
34
84-08 Vehicle Speed Out of Range 36 224-11 Theft Deterrent Enabled 00
84-10 Vehicle Speed Rate of Change 36 224-14 Engine Cranking / Theft Deterrent Enabled 00
91-08 Invalid Throttle Signal 32 231-11 J1939 Data Link Fault 58
91-13 Throttle Sensor Calibration 28 232-03 5 Volt Supply Above Normal 21
100-03 Oil Press Sensor Open Circuit 24 232-04 5 Volt Supply Below Normal 21
100-04 Oil Press Sensor Short Circuit 24 246-11 Service Brake Switch Number 1 Fault 00
100-11 Very Low Oil Press 46 247-11 Service Brake Switch Number 2 Fault 00
102-03 Boost Press Sensor Open Circuit 25 252-11 Incorrect Engine Software 59
102-04 Boost Press Sensor Short Circuit 25 253-02 Check Customer or System Parameters 59
Diagnostic Code Listing
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