wiring diagram INFINITI QX56 2004 Factory Repair Manual

EC-4Revision: August 20072004 QX56 Overall Function Check ........................................326
Diagnostic Procedure ...........................................327
DTC P0460 FUEL LEVEL SENSOR .......................334
Component Description ........................................334
On Board Diagnosis Logic ....................................334
DTC Confirmation Procedure ...............................334
Diagnostic Procedure ...........................................335
Removal and Installation ......................................335
DTC P0461 FUEL LEVEL SENSOR .......................336
Component Description ........................................336
On Board Diagnosis Logic ....................................336
Overall Function Check ........................................336
Diagnostic Procedure ...........................................337
Removal and Installation ......................................337
DTC P0462, P0463 FUEL LEVEL SENSOR CIR-
CUIT ........................................................................338
Component Description ........................................338
On Board Diagnosis Logic ....................................338
DTC Confirmation Procedure ...............................338
Diagnostic Procedure ...........................................339
Removal and Installation ......................................339
DTC P0500 VSS ......................................................340
Description ............................................................340
On Board Diagnosis Logic ....................................340
DTC Confirmation Procedure ...............................340
Overall Function Check ........................................340
Diagnostic Procedure ...........................................341
DTC P0506 ISC SYSTEM .......................................342
Description ............................................................342
On Board Diagnosis Logic ....................................342
DTC Confirmation Procedure ...............................342
Diagnostic Procedure ...........................................343
DTC P0507 ISC SYSTEM .......................................344
Description ............................................................344
On Board Diagnosis Logic ....................................344
DTC Confirmation Procedure ...............................344
Diagnostic Procedure ...........................................345
DTC P0550 PSP SENSOR ......................................346
Component Description ........................................346
CONSULT-II Reference Value in Data Monitor Mode
.346
On Board Diagnosis Logic ....................................346
DTC Confirmation Procedure ...............................346
Wiring Diagram .....................................................347
Diagnostic Procedure ...........................................348
Component Inspection ..........................................350
Removal and Installation ......................................350
DTC P0605 ECM .....................................................351
Component Description ........................................351
On Board Diagnosis Logic ....................................351
DTC Confirmation Procedure ...............................351
Diagnostic Procedure ...........................................352
DTC P1031, P1032, P1051, P1052 A/F SENSOR 1
HEATER ..................................................................354
Description ............................................................354
CONSULT-II Reference Value in Data Monitor Mode
.354
On Board Diagnosis Logic ....................................354
DTC Confirmation Procedure ...............................354Wiring Diagram ..................................................... 355
Diagnostic Procedure ............................................ 358
Component Inspection .......................................... 360
Removal and Installation ....................................... 360
DTC P1065 ECM POWER SUPPLY ........................ 361
Component Description ........................................ 361
On Board Diagnosis Logic .................................... 361
DTC Confirmation Procedure ................................ 361
Wiring Diagram ..................................................... 362
Diagnostic Procedure ............................................ 363
DTC P1121 ELECTRIC THROTTLE CONTROL
ACTUATOR ............................................................. 365
Component Description ........................................ 365
On Board Diagnosis Logic .................................... 365
DTC Confirmation Procedure ................................ 365
Diagnostic Procedure ............................................ 366
DTC P1122 ELECTRIC THROTTLE CONTROL
FUNCTION .............................................................. 367
Description ............................................................ 367
On Board Diagnosis Logic .................................... 367
DTC Confirmation Procedure ................................ 367
Wiring Diagram ..................................................... 368
Diagnostic Procedure ............................................ 369
Component Inspection .......................................... 372
Remove and Installation ....................................... 372
DTC P1124, P1126 THROTTLE CONTROL MOTOR
RELAY ..................................................................... 373
Component Description ........................................ 373
CONSULT-II Reference Value in Data Monitor Mode
. 373
On Board Diagnosis Logic .................................... 373
DTC Confirmation Procedure ................................ 373
Wiring Diagram ..................................................... 375
Diagnostic Procedure ............................................ 376
DTC P1128 THROTTLE CONTROL MOTOR ......... 378
Component Description ........................................ 378
On Board Diagnosis Logic .................................... 378
DTC Confirmation Procedure ................................ 378
Wiring Diagram ..................................................... 379
Diagnostic Procedure ............................................ 380
Component Inspection .......................................... 381
Removal and Installation ....................................... 382
DTC P1146, P1166 HO2S2 ..................................... 383
Component Description ........................................ 383
CONSULT-II Reference Value in Data Monitor Mode
. 383
On Board Diagnosis Logic .................................... 383
DTC Confirmation Procedure ................................ 384
Overall Function Check ......................................... 384
Wiring Diagram ..................................................... 386
Diagnostic Procedure ............................................ 389
Component Inspection .......................................... 392
Removal and Installation ....................................... 394
DTC P1147, P1167 HO2S2 ..................................... 395
Component Description ........................................ 395
CONSULT-II Reference Value in Data Monitor Mode
. 395
On Board Diagnosis Logic .................................... 395
DTC Confirmation Procedure ................................ 396

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Revision: August 20072004 QX56 Overall Function Check ........................................ 396
Wiring Diagram .................................................... 398
Diagnostic Procedure ........................................... 401
Component Inspection ......................................... 404
Removal and Installation ...................................... 406
DTC P1148, P1168 CLOSED LOOP CONTROL .... 407
On Board Diagnosis Logic ................................... 407
DTC P1211 TCS CONTROL UNIT ......................... 408
Description ........................................................... 408
On Board Diagnosis Logic ................................... 408
DTC Confirmation Procedure ............................... 408
Diagnostic Procedure ........................................... 408
DTC P1212 TCS COMMUNICATION LINE ............ 409
Description ........................................................... 409
On Board Diagnosis Logic ................................... 409
DTC Confirmation Procedure ............................... 409
Diagnostic Procedure ........................................... 409
DTC P1217 ENGINE OVER TEMPERATURE ....... 410
Description ........................................................... 410
CONSULT-II Reference Value in Data Monitor Mode
. 410
On Board Diagnosis Logic .................................... 411
Overall Function Check ......................................... 411
Wiring Diagram .................................................... 413
Diagnostic Procedure ........................................... 415
Main 12 Causes of Overheating ........................... 418
Component Inspection ......................................... 419
DTC P1225 TP SENSOR ........................................ 420
Component Description ........................................ 420
On Board Diagnosis Logic ................................... 420
DTC Confirmation Procedure ............................... 420
Diagnostic Procedure ........................................... 421
Removal and Installation ...................................... 421
DTC P1226 TP SENSOR ........................................ 422
Component Description ........................................ 422
On Board Diagnosis Logic ................................... 422
DTC Confirmation Procedure ............................... 422
Diagnostic Procedure ........................................... 423
Removal and Installation ...................................... 423
DTC P1229 SENSOR POWER SUPPLY ................ 424
On Board Diagnosis Logic ................................... 424
DTC Confirmation Procedure ............................... 424
Wiring Diagram .................................................... 425
Diagnostic Procedure ........................................... 426
DTC P1271, P1281 A/F SENSOR 1 ....................... 429
Component Description ........................................ 429
CONSULT-II Reference Value in Data Monitor Mode
. 429
On Board Diagnosis Logic ................................... 429
DTC Confirmation Procedure ............................... 429
Wiring Diagram .................................................... 431
Diagnostic Procedure ........................................... 434
Removal and Installation ...................................... 436
DTC P1272, P1282 A/F SENSOR 1 ....................... 437
Component Description ........................................ 437
CONSULT-II Reference Value in Data Monitor Mode
. 437
On Board Diagnosis Logic ................................... 437
DTC Confirmation Procedure ............................... 437Wiring Diagram .....................................................439
Diagnostic Procedure ...........................................442
Removal and Installation ......................................444
DTC P1273, P1283 A/F SENSOR 1 .......................445
Component Description ........................................445
CONSULT-II Reference Value in Data Monitor Mode
.445
On Board Diagnosis Logic ....................................445
DTC Confirmation Procedure ...............................445
Wiring Diagram .....................................................447
Diagnostic Procedure ...........................................450
Removal and Installation ......................................453
DTC P1274, P1284 A/F SENSOR 1 .......................454
Component Description ........................................454
CONSULT-II Reference Value in Data Monitor Mode
.454
On Board Diagnosis Logic ....................................454
DTC Confirmation Procedure ...............................454
Wiring Diagram .....................................................456
Diagnostic Procedure ...........................................459
Removal and Installation ......................................462
DTC P1276, P1286 A/F SENSOR 1 .......................463
Component Description ........................................463
CONSULT-II Reference Value in Data Monitor Mode
.463
On Board Diagnosis Logic ....................................463
DTC Confirmation Procedure ...............................463
Overall Function Check ........................................464
Wiring Diagram .....................................................466
Diagnostic Procedure ...........................................469
Removal and Installation ......................................471
DTC P1278, P1288 A/F SENSOR 1 .......................472
Component Description ........................................472
CONSULT-II Reference Value in Data Monitor Mode
.472
On Board Diagnosis Logic ....................................472
DTC Confirmation Procedure ...............................473
Wiring Diagram .....................................................475
Diagnostic Procedure ...........................................478
Removal and Installation ......................................483
DTC P1279, P1289 A/F SENSOR 1 .......................484
Component Description ........................................484
CONSULT-II Reference Value in Data Monitor Mode
.484
On Board Diagnosis Logic ....................................484
DTC Confirmation Procedure ...............................485
Wiring Diagram .....................................................487
Diagnostic Procedure ...........................................490
Removal and Installation ......................................495
DTC P1444 EVAP CANISTER PURGE VOLUME
CONTROL SOLENOID VALVE ...............................496
Description ............................................................496
CONSULT-II Reference Value in Data Monitor Mode
.496
On Board Diagnosis Logic ....................................497
DTC Confirmation Procedure ...............................497
Wiring Diagram .....................................................498
Diagnostic Procedure ...........................................500

EC-6Revision: August 20072004 QX56 Component Inspection ..........................................503
Removal and Installation ......................................503
DTC P1446 EVAP CANISTER VENT CONTROL
VALVE .....................................................................504
Component Description ........................................504
CONSULT-II Reference Value in Data Monitor Mode
.504
On Board Diagnosis Logic ....................................504
DTC Confirmation Procedure ...............................505
Wiring Diagram .....................................................506
Diagnostic Procedure ...........................................507
Component Inspection ..........................................508
DTC P1564 ICC STEERING SWITCH ....................510
Component Description ........................................510
CONSULT-II Reference Value in Data Monitor Mode
.510
On Board Diagnosis Logic ....................................510
DTC Confirmation Procedure ...............................510
Wiring Diagram .....................................................512
Diagnostic Procedure ...........................................514
Component Inspection ..........................................516
DTC P1564 ASCD STEERING SWITCH ................517
Component Description ........................................517
CONSULT-II Reference Value in Data Monitor Mode
.517
On Board Diagnosis Logic ....................................517
DTC Confirmation Procedure ...............................518
Wiring Diagram .....................................................519
Diagnostic Procedure ...........................................521
Component Inspection ..........................................522
DTC P1568 ICC FUNCTION ...................................524
On Board Diagnosis Logic ....................................524
DTC Confirmation Procedure ...............................524
Diagnostic Procedure ...........................................524
DTC P1572 ICC BRAKE SWITCH ..........................525
Component Description ........................................525
CONSULT-II Reference Value in Data Monitor Mode
.525
On Board Diagnosis Logic ....................................525
DTC Confirmation Procedure ...............................525
Wiring Diagram .....................................................527
Diagnostic Procedure ...........................................528
Component Inspection ..........................................532
DTC P1572 ASCD BRAKE SWITCH ......................534
Component Description ........................................534
CONSULT-II Reference Value in Data Monitor Mode
.534
On Board Diagnosis Logic ....................................534
DTC Confirmation Procedure ...............................535
Wiring Diagram .....................................................536
Diagnostic Procedure ...........................................537
Component Inspection ..........................................541
DTC P1574 ICC VEHICLE SPEED SENSOR .........542
Component Description ........................................542
On Board Diagnosis Logic ....................................542
DTC Confirmation Procedure ...............................542
Diagnostic Procedure ...........................................543
DTC P1574 ASCD VEHICLE SPEED SENSOR .....544
Component Description ........................................544On Board Diagnosis Logic .................................... 544
DTC Confirmation Procedure ................................ 544
Diagnostic Procedure ............................................ 545
DTC P1706 PNP SWITCH ....................................... 546
Component Description ........................................ 546
CONSULT-II Reference Value in Data Monitor Mode
. 546
On Board Diagnosis Logic .................................... 546
DTC Confirmation Procedure ................................ 546
Overall Function Check ......................................... 547
Wiring Diagram ..................................................... 548
Diagnostic Procedure ............................................ 549
DTC P1805 BRAKE SWITCH ................................. 551
Description ............................................................ 551
CONSULT-II Reference Value in Data Monitor Mode
. 551
On Board Diagnosis Logic .................................... 551
DTC Confirmation Procedure ................................ 551
Wiring Diagram ..................................................... 552
Diagnostic Procedure ............................................ 553
Component Inspection .......................................... 555
DTC P2122, P2123 APP SENSOR ......................... 556
Component Description ........................................ 556
CONSULT-II Reference Value in Data Monitor Mode
. 556
On Board Diagnosis Logic .................................... 556
DTC Confirmation Procedure ................................ 557
Wiring Diagram ..................................................... 558
Diagnostic Procedure ............................................ 559
Component Inspection .......................................... 561
Removal and Installation ....................................... 561
DTC P2127, P2128 APP SENSOR ......................... 562
Component Description ........................................ 562
CONSULT-II Reference Value in Data Monitor Mode
. 562
On Board Diagnosis Logic .................................... 562
DTC Confirmation Procedure ................................ 563
Wiring Diagram ..................................................... 564
Diagnostic Procedure ............................................ 565
Component Inspection .......................................... 568
Removal and Installation ....................................... 568
DTC P2135 TP SENSOR ........................................ 569
Component Description ........................................ 569
CONSULT-II Reference Value in Data Monitor Mode
. 569
On Board Diagnosis Logic .................................... 569
DTC Confirmation Procedure ................................ 570
Wiring Diagram ..................................................... 571
Diagnostic Procedure ............................................ 572
Component Inspection .......................................... 575
Removal and Installation ....................................... 575
DTC P2138 APP SENSOR ...................................... 576
Component Description ........................................ 576
CONSULT-II Reference Value in Data Monitor Mode
. 576
On Board Diagnosis Logic .................................... 576
DTC Confirmation Procedure ................................ 577
Wiring Diagram ..................................................... 578
Diagnostic Procedure ............................................ 579

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Revision: August 20072004 QX56 Component Inspection ......................................... 582
Removal and Installation ...................................... 582
IGNITION SIGNAL .................................................. 583
Component Description ........................................ 583
Wiring Diagram .................................................... 584
Diagnostic Procedure ........................................... 589
Component Inspection ......................................... 593
Removal and Installation ...................................... 594
INJECTOR CIRCUIT ............................................... 595
Component Description ........................................ 595
CONSULT-II Reference Value in Data Monitor Mode
. 595
Wiring Diagram .................................................... 596
Diagnostic Procedure ........................................... 597
Component Inspection ......................................... 600
Removal and Installation ...................................... 600
FUEL PUMP CIRCUIT ............................................ 601
Description ........................................................... 601
CONSULT-II Reference Value in Data Monitor Mode
. 601
Wiring Diagram .................................................... 602
Diagnostic Procedure ........................................... 603
Component Inspection ......................................... 606
Removal and Installation ...................................... 606
REFRIGERANT PRESSURE SENSOR ................. 607
Component Description ........................................ 607
Wiring Diagram .................................................... 608
Diagnostic Procedure ........................................... 609
Removal and Installation ....................................... 611
ELECTRICAL LOAD SIGNAL ................................ 612
Description ........................................................... 612
CONSULT-II Reference Value in Data Monitor Mode
. 612
Diagnostic Procedure ........................................... 612
ICC BRAKE SWITCH ............................................. 613
Component Description ........................................ 613
CONSULT-II Reference Value in Data Monitor Mode
. 613
Wiring Diagram .................................................... 614
Diagnostic Procedure ........................................... 615
Component Inspection ......................................... 619
ASCD BRAKE SWITCH ......................................... 621
Component Description ........................................ 621CONSULT-II Reference Value in Data Monitor Mode
.621
Wiring Diagram .....................................................622
Diagnostic Procedure ...........................................623
Component Inspection ..........................................627
ASCD INDICATOR ..................................................628
Component Description ........................................628
CONSULT-II Reference Value in Data Monitor Mode
.628
Wiring Diagram .....................................................629
Diagnostic Procedure ...........................................630
MIL AND DATA LINK CONNECTOR ......................631
Wiring Diagram .....................................................631
EVAPORATIVE EMISSION SYSTEM .....................633
Description ............................................................633
Component Inspection ..........................................636
Removal and Installation ......................................637
How to Detect Fuel Vapor Leakage ......................637
ON BOARD REFUELING VAPOR RECOVERY
(ORVR) ....................................................................640
System Description ...............................................640
Diagnostic Procedure ...........................................641
Component Inspection ..........................................643
POSITIVE CRANKCASE VENTILATION ...............645
Description ............................................................645
Component Inspection ..........................................645
AUTOMATIC SPEED CONTROL DEVICE (ASCD) .647
System Description ...............................................647
Component Description ........................................648
SERVICE DATA AND SPECIFICATIONS (SDS) ....649
Fuel Pressure .......................................................649
Idle Speed and Ignition Timing .............................649
Calculated Load Value ..........................................649
Mass Air Flow Sensor ...........................................649
Intake Air Temperature Sensor .............................649
Engine Coolant Temperature Sensor ...................649
A/F Sensor 1 Heater .............................................649
Heated Oxygen sensor 2 Heater ..........................649
Crankshaft Position Sensor (POS) .......................649
Camshaft Position Sensor (PHASE) ....................649
Throttle Control Motor ...........................................649
Injector ..................................................................650
Fuel Pump ............................................................650

PRECAUTIONS
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Do not operate fuel pump when there is no fuel in lines.

Tighten fuel hose clamps to the specified torque.

Do not depress accelerator pedal when starting.

Immediately after starting, do not rev up engine unneces-
sarily.

Do not rev up engine just prior to shutdown.

When installing C.B. ham radio or a mobile phone, be sure
to observe the following as it may adversely affect elec-
tronic control systems depending on installation location.
–Keep the antenna as far as possible from the electronic
control units.
–Keep the antenna feeder line more than 20 cm (8 in) away
from the harness of electronic controls.
Do not let them run parallel for a long distance.
–Adjust the antenna and feeder line so that the standing-
wave radio can be kept smaller.
–Be sure to ground the radio to vehicle body.
Wiring Diagrams and Trouble DiagnosisUBS00GZ8
When you read wiring diagrams, refer to the following:

GI-15, "How to Read Wiring Diagrams"

PG-4, "POWER SUPPLY ROUTING CIRCUIT" for power distribution circuit
When you perform trouble diagnosis, refer to the following:

GI-11, "HOW TO FOLLOW TEST GROUPS IN TROUBLE DIAGNOSES"

GI-27, "How to Perform Efficient Diagnosis for an Electrical Incident"
BBIA0402E
SEF 7 09 Y
SEF 7 08 Y

BASIC SERVICE PROCEDURE
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21. CHECK AIR FUEL RATIO (A/F) SENSOR 1 HARNESS
1. Turn ignition switch OFF and disconnect battery ground cable.
2. Disconnect ECM harness connector.
3. Disconnect A/F sensor 1 harness connector.
4. Check harness continuity between the following terminals. Refer to EC-431, "
Wiring Diagram" .
5. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 22.
NG >> 1. Repair open circuit or short to ground or short to power in harness or connectors between ECM
and A/F sensor 1.
2. GO TO 4.
22. PERFORM ACCELERATOR PEDAL RELEASED POSITION LEARNING
1. Reconnect ECM harness connector.
2. Perform EC-44, "
Accelerator Pedal Released Position Learning" .
>> GO TO 23.
23. PERFORM THROTTLE VALVE CLOSED POSITION LEARNING
Perform EC-44, "
Throttle Valve Closed Position Learning" .
>> GO TO 24.
24. PERFORM IDLE AIR VOLUME LEARNING
Refer to EC-44, "
Idle Air Volume Learning" .
Is Idle Air Volume Learning carried out successfully?
Ye s o r N o
Yes (With CONSULT-II)>>GO TO 25.
Yes (Without CONSULT-II)>>GO TO 26.
No >> 1. Follow the instruction of Idle Air Volume Learning.
2. GO TO 4.
Bank 1 Bank 2
A/F sensor 1 terminal ECM terminal A/F sensor 1 terminal ECM terminal
1161 76
275277
42424
535557
656658
Continuity should exist.

EC-128Revision: August 2007
POWER SUPPLY AND GROUND CIRCUIT
2004 QX56
POWER SUPPLY AND GROUND CIRCUITPFP:24110
Wiring DiagramUBS00H0F
BBWA11 55 E

EC-130Revision: August 2007
POWER SUPPLY AND GROUND CIRCUIT
2004 QX56
4. DETECT MALFUNCTIONING PART
Check the following.

10A fuse

Harness for open or short between ECM and ignition switch
>> Repair harness or connectors.
5. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 6.
NG >> Repair or replace ground connections.
6. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-I
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminals 1, 115, 116 and body ground.
Refer to Wiring Diagram.
3. Also check harness for short to power.
OK or NG
OK >> GO TO 8.
NG >> GO TO 7.
7. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors F32, E2

Harness for open or short between ECM and body ground
>> Repair open circuit or short to power in harness or connectors.
BBIA0354E
Continuity should exist.

EC-132Revision: August 2007
POWER SUPPLY AND GROUND CIRCUIT
2004 QX56
11 . CHECK ECM POWER SUPPLY CIRCUIT-V
1. Disconnect ECM harness connector.
2. Disconnect IPDM E/R harness connector E119.
3. Check harness continuity between ECM terminals 119, 120 and IPDM E/R terminal 3.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 14.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
12. CHECK ECM POWER SUPPLY CIRCUIT-VI
1. Disconnect ECM harness connector.
2. Disconnect IPDM E/R harness connector E119.
3. Check harness continuity between ECM terminal 111 and IPDM E/R terminal 7.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 13.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
13. CHECK 20A FUSE
Check 20A fuse (No. 53, located in the IPDM E/R).
OK or NG
OK >> GO TO 17.
NG >> Replace 20A fuse.
14. CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
Refer to EC-133, "
Ground Inspection" .
OK or NG
OK >> GO TO 15.
NG >> Repair or replace ground connections.Continuity should exist.
Continuity should exist.
BBIA0354E

POWER SUPPLY AND GROUND CIRCUIT
EC-133
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15. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-II
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminals 1, 115, 116 and ground.
Refer to Wiring Diagram.
3. Also check harness for short to power.
OK or NG
OK >> GO TO 17.
NG >> GO TO 16.
16. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors F32, E2

Harness for open or short between ECM and ground
>> Repair open circuit or short to power in harness or connectors.
17. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
OK or NG
OK >> Replace IPDM E/R.
NG >> Repair open circuit or short to power in harness or connectors.
Ground Inspection UBS00H0H
Ground connections are very important to the proper operation of electrical and electronic circuits. Ground
connections are often exposed to moisture, dirt and other corrosive elements. The corrosion (rust) can
become an unwanted resistance. This unwanted resistance can change the way a circuit works.
Electronically controlled circuits are very sensitive to proper grounding. A loose or corroded ground can drasti-
cally affect an electronically controlled circuit. A poor or corroded ground can easily affect the circuit. Even
when the ground connection looks clean, there can be a thin film of rust on the surface.
When inspecting a ground connection follow these rules:

Remove the ground bolt or screw.

Inspect all mating surfaces for tarnish, dirt, rust, etc.

Clean as required to assure good contact.

Reinstall bolt or screw securely.

Inspect for “add-on” accessories which may be interfering with the ground circuit.

If several wires are crimped into one ground eyelet terminal, check for proper crimps. Make sure all of the
wires are clean, securely fastened and providing a good ground path. If multiple wires are cased in one
eyelet make sure no ground wires have excess wire insulation.Continuity should exist.