cat 3126 eletric diagrama

©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


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



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 ATMOSPHERIC PRESSURE



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 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



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



J1939 DATA LINK SHIELD



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


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



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


34

84-02 Invalid Vehicle Speed Signal 36 190-11 No Pattern on Engine Speed


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

cat 3126 eletric diagrama

Documents