GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 TopKick C-Series (Conventional) C6/C7/C8 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 Harness Routing Views
Figure 1:

Forward Lamp Harness - Left/Right Routing - V22 Shown, GRW Similar
Object Number: 1593957 Size: LF
(1)S144
(2)Core Support
(3)LH Frame Rail
(4)S117
(5)C107 (5 cavities) Chassis Harness to Forward Lamp Harness - Left
(6)C108 (5 cavities) Chassis Harness to Forward Lamp Harness - Right
(7)S143
Figure 2:

Exhaust Brake Harness - K40/NPE
Object Number: 1559010 Size: LF
(1)Radiator Fan Shroud
(2)Exhaust Brake Relay (K40/NPE w/o LLY)
(3)C104 (6 cavities - LG4/LG5/LLY) Engine Chassis Harness to the Exhaust Brake Harness
(4)Exhaust Brake Harness (K40/NPE)
(5)Exhaust Brake Actuator Control Solenoid Valve (K40/NPE)
(6)Exhaust Throttle
(7)Exhaust Brake Actuator (K40/NPE)
Figure 3:

Chassis Front Engine Compartment
Object Number: 1558088 Size: LF
(1)C108 (5 cavities) Chassis Harness to the Forward Lamp Harness - Right
(2)C106 (6 cavities - C4/C5) Radiator Harness to the Chassis Harness or C106 (12 cavities - C6/C7/C8) Chassis Harness to the Radiator Harness
(3)G100
(4)Wheel Speed Sensor (WSS) - RF Connector
(5)C100 (30 cavities) Chassis Harness to the Engine Harness
(6)C126 (40 cavities) Chassis Harness to I/P Harness
(7)Brake Fluid Level Switch (JE3)
(8)Power Brake (P/B) Booster Fluid Flow Switch (JE3)
(9)Hydromax® Relay (JE3)
(10)C410 (3 cavities) Chassis Harness to Air Compressor Harness (K16)
(11)Wheel Speed Sensor (WSS) - LF Connector
(12)Electronic Brake Control Module (EBCM) Connector
(13)C107 (5 cavities) Chassis Harness to Forward Lamp Harness - Left
Figure 4:

A/C Harness Routing - LLY Shown, Others Similar
Object Number: 1593953 Size: LF
(1)A/C Accumulator/Dehydrator
(2)C105 Engine Harness to A/C Harness
(3)A/C Compressor Clutch Diode
(4)A/C Compressor Clutch Relay
Figure 5:

A/C Compressor Harness - L18 Shown, Others Similar
Object Number: 1557644 Size: LF
(1)A/C Compressor Harness
(2)A/C High Pressure Switch Connector
(3)A/C Compressor
(4)S148
(5)A/C Compressor Clutch Diode
(6)A/C Compressor Clutch Connector
(7)Engine Harness
(8)S147
(9)A/C Compressor Clutch Relay
(10)A/C Low Pressure Switch Connector
Figure 6:

Connectors C118 and C119
Object Number: 1195994 Size: LF
(1)C118 (40 cavities) Engine Harness to the Engine Chassis Harness
(2)C119 (24 cavities) Engine Harness to the Engine Chassis Harness
Figure 7:

Lower Right Side of the Engine
Object Number: 1217665 Size: MF
(1)G118
(2)Engine Block
(3)G120
(4)G119
Figure 8:

Battery Cable Harness Routing (L18/TNL/TNN)
Object Number: 1593954 Size: LF
(1)LH Frame Rail
(2)Junction Block - Underhood
(3)G100
(4)Battery Box
Figure 9:

Back Right of the Engine Compartment (L18)
Object Number: 822091 Size: LF
(1)C101
(2)C124
(3)Engine Harness
(4)C124
(5)I/P Harness
(6)C101
Figure 10:

Engine Chassis Harness - 1 of 2 (LLY)
Object Number: 1807009 Size: LF
(1)C121
(2)S163
(3)S114
(4)To Underhood Junction Block
(5)S118
(6)Fuse Block - Underhood (Primary)
(7)Engine Control Module C2
(8)Engine Control Module C1
(9)Transmission Control Module (TCM) (w/A/T)
(10)Mass Aif Flow/ Intake Air Temperature (MAF/IAT) Sensor
(11)C105
(12)Starter
(13)Turbine Shaft Speed (TSS) Sensor Connector
(14)S166
(15)Vehicle Speed Sensor (VSS) Connector
(16)C175
(17)C100
(18)C102
(19)C124
(20)C101
(21)S107
(22)S121
(23)S102
(24)S101
(25)S103
(26)S100
(27)S120
Figure 11:

Engine Chassis Harness - 2 of 2 (LLY)
Object Number: 1807012 Size: LF
(1)Fuse Block - Underhood (Primary)
(2)S110
(3)C119
(4)C175
(5)C118
(6)S105
(7)S106
Figure 12:

Engine Harness (LLY)
Object Number: 1808808 Size: LF
(1)C134
(2)C133
(3)C119
(4)C118
(5)C113
Figure 13:

Body/Roof Harness Routing - w/o Crew Cab
Object Number: 1593956 Size: LF
(1)Cab Panel
(2)C203 (16 cavities) I/P Harness to Body/Roof Harness
(3)S324
(4)Floor Panel
(5)C315 (2 cavities) Console Harness to Body/Roof Harness
Figure 14:

Body/Roof Harness Routing - Crew Cab
Object Number: 1593955 Size: LF
(1)C301 (12 cavities) Body/Roof Harness to Rear Door Harness - Left
(2)S302
(3)S325
(4)S326
(5)C203 I/P Harness to Body/Roof Harness
(6)S324
(7)S312
(8)S310
(9)S308
(10)S322
(11)S335
(12)C302 (12 cavities) Body/Roof Harness to Rear Door Harness - Right
(13)Floor Panel
(14)Blower Motor Relay - Auxiliary (C36)
Figure 15:

I/P Harness 1 of 3
Object Number: 1559694 Size: LF
(1)S261
(2)S232
(3)S264
(4)S259
(5)S217
(6)S204
(7)S252
(8)S223
(9)S202
(10)S412
(11)S220
(12)S203
(13)S222
(14)S253
(15)S230
(16)C206 (4 cavities) I/P Harness to the Body/Roof Harness
(17)G101
(18)Park Brake Switch Connector (C4/C5 and JE3) or C210 (2 cavities) I/P Harness to the Park Brake Harness (C6/C7/C8 and JE3)
(19)C203 (16 cavities) I/P Harness to Body/Roof Harness
(20)S240
Figure 16:

I/P Harness 2 of 3
Object Number: 1559700 Size: LF
(1)SP203 (12 cavities)
(2)C209 (3 cavities - Crew Cab) Body/Roof Harness to the I/P Harness
(3)S249
(4)S219
(5)S211
(6)S222
(7)S213
(8)S200
(9)S212
(10)S273
(11)S274
(12)S214
(13)S255
(14)S245
(15)C202 (30 cavities) I/P Switchbank Harness to the I/P Harness
(16)S210
(17)Data Link Connector (DLC)
(18)S216
(19)C201 (48 cavities) Steering Column Harness to the I/P Harness
(20)S207
Figure 17:

I/P Harness 3 of 3
Object Number: 1559702 Size: LF
(1)Fuse Block-Underhood (Secondary)
(2)C207 (30 cavities) I/P Harness to Cross Body Harness
(3)C109 (40 cavities - L18/LG4/LG5) Engine Chassis Harness to the I/P Harness
(4)C101 (30 cavities) I/P Harness to the Engine Chassis Harness
(5)S269
(6)S218
(7)S260
(8)Junction Block - Underhood Ring Terminal
Figure 18:

I/P Switchbank Harness
Object Number: 1559703 Size: LF
(1)S251
(2)S236
(3)S285
(4)S239
(5)S900
(6)S258
(7)C202 (30 cavities) I/P Switchbank Harness to the I/P Harness
(8)S235
Figure 19:

Cross Body Harness - Left
Object Number: 1559143 Size: LF
(1)C208 (6 cavities) Cross Body Harness to the Stop Lamp Switch Harness
(2)Clutch Pedal Position (CPP) Switch
(3)C211 (22 cavities) Door Harness - Driver to the Cross Body Harness
(4)Cross Body Harness
Figure 20:

Cross Body Harness - Right
Object Number: 1559155 Size: LF
(1)S219
(2)S300
(3)S506
(4)S500
(5)C212 (22 cavities) Door Harness - Passenger to the Cross Body Harness
(6)G103
(7)C207 (30 cavities) I/P Harness to the Cross Body Harness
Figure 21:

Console Harness
Object Number: 1559802 Size: LF
(1)Console
(2)C315 (2 cavities) Console Harness to the Body/Roof Harness
Figure 22:

Park Brake Harness - C6/C7/C8 and JE3
Object Number: 1559807 Size: LF
(1)C210 (2 cavities) I/P Harness to the Park Brake Harness
(2)Park Brake Assembly
(3)Floor Panel
Figure 23:

Door Harness - Driver 1 of 2
Object Number: 1559020 Size: LF
(1)Window Motor - Driver (A31)
(2)C211 (22 cavities) Door Harness - Driver to the Cross Body Harness
(3)C215 (8 cavities) Door Harness - Driver to the Mirror Harness
(4)C217 (8 cavities) Door Harness - Driver to the Cross Body Harness
(5)Door Latch Assembly - Driver Connector C2 (4 cavities - AU3)
(6)Door Latch Assembly - Driver (2 cavities - w/o AU3) or Door Latch Assembly - Driver Connector C1 (2 cavities - AU3)
Figure 24:

Door Harness - Driver 2 of 2
Object Number: 1559022 Size: LF
(1)S503
(2)S504
(3)S505
(4)S500
(5)S502
(6)S501
(7)Door Lock Switch - Driver (AU3) and Window Switch - Driver (A31/Crew Cab)
(8)Speaker - LF Tweeter (ZQ2)
(9)Outside Rearview Mirror Switch (DB6)
Figure 25:

Door Harness - Passenger 1 of 2
Object Number: 1559015 Size: LF
(1)Door Latch Assembly - Passenger (2 cavities - w/o AU3) or Door Latch Assembly - Passenger Connector C1 (2 cavities - AU3)
(2)Door Latch Assembly - Passenger Connector C2 (4 cavities - AU3)
(3)C216 (8 cavities) Door Harness - Passenger to the Mirror Harness
(4)C212 (22 cavities) Door Harness - Passenger to the Cross Body Harness
(5)Window Motor - Passenger (A31)
Figure 26:

Door Harness - Passenger 2 of 2
Object Number: 1559018 Size: LF
(1)S608
(2)S604
(3)S603
(4)S604
(5)S602
(6)Door Lock Switch - Passenger (AU3) and Window Switch - Passenger (A31/Crew Cab)
(7)Speaker - RF Tweeter (ZQ2)
Figure 27:

Chassis Harness Middle Right Frame Rail - Crew Cab Shown, Others Similar
Object Number: 1818384 Size: LF
(1)S431
(2)S430
(3)C409
(4)S319
(5)Splice Pack SP400
(6)S402
(7)C305 - Upfitter Lighting Connector
Figure 28:

Chassis Harness Right Rear Frame Rail
Object Number: 1558182 Size: LF
(1)C412 (8 cavities) Tail Lamp Harness to the Chassis Harness (w/o UZF) or C413 (8 cavities) Tail Lamp Harness to the Backup Alarm Harness (UZF)
(2)Wheel Speed Sensor (WSS) Connector - RR
(3)C409 (8 cavities) Fuel Tank Harness to the Chassis Harness
Figure 29:

Chassis Harness, Rear of Vehicle (JE4)
Object Number: 1861730 Size: LF
(1)Chassis Harness
(2)C406
(3)C401
(4)ABS Harness
Figure 30:

Air Compressor (K16), Fuel Tanks and Trailer Connector (RQ2 and U86 or RQ3)
Object Number: 1014827 Size: LF
(1)Splice Pack SP400 (Ground Block)
(2)C409 (8 cavities) Fuel Tank Harness to the Chassis Harness
(3)Fuel Pump (FP) Relay
(4)Fuel Sender - Secondary
(5)Fuel Tank Transfer Pump - Secondary
(6)Trailer Connector (RQ2 and U86 or RQ3)
(7)C410 (3 cavities - K16) Chassis Harness to the Air Compressor Harness
(8)Air Compressor Connector (K16)
(9)Air Compressor Relay (K16)
(10)Air Compressor (K16)
(11)Fuel Sender - Primary
Figure 31:

Fuel Tank Harness Routing (L18/NK1)
Object Number: 1594015 Size: LF
(1)RH Frame Rail
(2)C409 (8 cavities) Fuel Tank Harness to the Chassis Harness
(3)G408
(4)C406 (4 cavities - HPZ/HR1/HR2) Chassis Harness to the Rear Axle Harness
(5)Fuel Tank
Figure 32:

Fuel Sender Harness
Object Number: 1559707 Size: LF
(1)S418
(2)S407
(3)C420 Fuel Sender Harness to Chassis Harness
(4)S420
(5)G400
(6)Fuel Tank - Secondary
(7)S408
(8)Fuel Tank - Primary
Figure 33:

Tail Lamp Harness and Backup Alarm Harness - UZF
Object Number: 953510 Size: LF
(1)Backup Alarm (UZF)
(2)S410
(3)C412 (8 cavities w/o UZF) Tail Lamp Harness to the Rear Chassis Harness or C413 (8 cavities UZF) Tail Lamp Harness to the Backup Alarm Harness
(4)Tail Lamp Assembly - Right
(5)S411
(6)Tail Lamp Assembly - Left