Lighting Systems: Other Chevrolet Silverado 2500 HD

Backup Lamp - Right Rear

Backup Lamp - Right Rear Connector Parts Information

Backup Lamp - Right Rear Connector Terminal Identification

Scheme 50

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X1 Connector Parts Information

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X1 Connector Terminal Identification

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X2

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X2 Connector Parts Information

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X2 Connector Terminal Identification

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X3

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X3 Connector Parts Information

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X3 Connector Terminal Identification

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X4

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X4 Connector Parts Information

Cargo Lamp/Center High Mounted Stop Lamp (CHMSL) X4 Connector Terminal Identification

Scheme 51

Clearance Lamp - Left Front (RO5) Connector Parts Information

Clearance Lamp - Left Front (RO5) Connector Terminal Identification

Clearance Lamp - Left Rear (RO5)

Clearance Lamp - Left Rear (RO5) Connector Parts Information

Clearance Lamp - Left Rear (RO5) Connector Terminal Identification

Clearance Lamp - Right Front (RO5)

Clearance Lamp - Right Front (RO5) Connector Parts Information

Clearance Lamp - Right Front (RO5) Connector Terminal Identification

Clearance Lamp - Right Rear (RO5)

Clearance Lamp - Right Rear (RO5) Connector Parts Information

Clearance Lamp - Right Rear (RO5) Connector Terminal Identification

Clearance Lamps (U01)

Clearance Lamps (U01) Connector Parts Information

Clearance Lamps (U01) Connector Terminal Identification

Scheme 52

Courtesy/Reading Lamps - Front Connector Parts Information

Courtesy/Reading Lamps - Front Connector Terminal Identification

Courtesy/Reading Lamps - Rear (Extended Cab/Crew Cab)

Courtesy/Reading Lamps - Rear (Extended Cab/Crew Cab) Connector Parts Information

Courtesy/Reading Lamps - Rear (Extended Cab/Crew Cab) Connector Terminal Identification

Scheme 53

Fog Lamp - Left Front (T96) Connector Parts Information

Fog Lamp - Left Front (T96) Connector Terminal Identification

Fog Lamp - Right Front (T96)

Fog Lamp - Right Front (T96) Connector Parts Information

Fog Lamp - Right Front (T96) Connector Terminal Identification

Scheme 54

Head Lamp - High Beam - Left Connector Parts Information

Head Lamp - High Beam - Left Connector Terminal Identification

Head Lamp - High Beam - Right

Head Lamp - High Beam - Right Connector Parts Information

Head Lamp - High Beam - Right Connector Terminal Identification

Scheme 55

Head Lamp - Low Beam - Left Connector Parts Information

Head Lamp - Low Beam - Left Connector Terminal Identification

Head Lamp - Low Beam - Right

Head Lamp - Low Beam - Right Connector Parts Information

Head Lamp - Low Beam - Right Connector Terminal Identification

Scheme 56

Headlamp and Panel Dimmer Switch Connector Parts Information

Headlamp and Panel Dimmer Switch Connector Terminal Identification

Scheme 57

License Lamp - Left Connector Parts Information

License Lamp - Left Connector Terminal Identification

License Lamp - Right

License Lamp - Right Connector Parts Information

License Lamp - Right Connector Terminal Identification

Marker Lamp - Left Front (Z88)

Marker Lamp - Left Front (Z88) Connector Parts Information

Marker Lamp - Left Front (Z88) Connector Terminal Identification

Marker Lamp - Right Front (Z88)

Marker Lamp - Right Front (Z88) Connector Parts Information

Marker Lamp - Right Front (Z88) Connector Terminal Identification

Scheme 58

Marker Lamp - Tailgate (RO5) Connector Parts Information

Marker Lamp - Tailgate (RO5) Connector Terminal Identification

Scheme 59

Marker Lamp - Left Rear (Z88) Connector Parts Information

Marker Lamp - Left Rear (Z88) Connector Terminal Identification

Marker Lamp - Right Rear (Z88)

Marker Lamp - Right Rear (Z88) Connector Parts Information

Marker Lamp - Right Rear (Z88) Connector Terminal Identification

Scheme 60

Park/Turn Signal Lamp - Left Front Lower Connector Parts Information

Park/Turn Signal Lamp - Left Front Lower Connector Terminal Identification

Park/Turn Signal Lamp - Left Front Upper

Park/Turn Signal Lamp - Left Front Upper Connector Parts Information

Park/Turn Signal Lamp - Left Front Upper Connector Terminal Identification

Park/Turn Signal Lamp - Right Front Lower

Park/Turn Signal Lamp - Right Front Lower Connector Parts Information

Park/Turn Signal Lamp - Right Front Lower Connector Terminal Identification

Park/Turn Signal Lamp - Right Front Upper

Park/Turn Signal Lamp - Right Front Upper Connector Parts Information

Park/Turn Signal Lamp - Right Front Upper Connector Terminal Identification

Roof Marker Lamp - Left (U01)

Roof Marker Lamp - Left (U01) Connector Parts Information

Roof Marker Lamp - Left (U01) Connector Terminal Identification

Roof Marker Lamp - Right (U01)

Roof Marker Lamp - Right (U01) Connector Parts Information

Roof Marker Lamp - Right (U01) Connector Terminal Identification

Scheme 61

Stop Lamp Switch Connector Parts Information

Stop Lamp Switch Connector Terminal Identification

Scheme 62

Sunshade - Left (DH6) Connector Parts Information

Sunshade - Left (DH6) Connector Terminal Identification

Sunshade - Right (DH6)

Sunshade - Right (DH6) Connector Parts Information

Sunshade - Right (DH6) Connector Terminal Identification

Scheme 63

Tail/Stop and Turn Signal Lamp - Lower Left Connector Parts Information

Tail/Stop and Turn Signal Lamp - Lower Left Connector Terminal Identification

Tail/Stop and Turn Signal Lamp - Lower Right

Tail/Stop and Turn Signal Lamp - Lower Right Connector Parts Information

Tail/Stop and Turn Signal Lamp - Lower Right Connector Terminal Identification

Tail/Stop and Turn Signal Lamp - Upper Left

Tail/Stop and Turn Signal Lamp - Upper Left Connector Parts Information

Tail/Stop and Turn Signal Lamp - Upper Left Connector Terminal Identification

Tail/Stop and Turn Signal Lamp - Upper Right

Tail/Stop and Turn Signal Lamp - Upper Right Connector Parts Information

Tail/Stop and Turn Signal Lamp - Upper Right Connector Terminal Identification

Scheme 64

Turn Signal/Multifunction Switch X1 Connector Parts Information

Turn Signal/Multifunction Switch X1 Connector Terminal Identification

Scheme 65

Turn Signal/Multifunction Switch X2 Connector Parts Information

Turn Signal/Multifunction Switch X2 Connector Terminal Identification

Scheme 66

Turn Signal/Malfunction Switch X3 Connector Parts Information

Turn Signal/Malfunction Switch X3 Connector Terminal Identification

Reference Information

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Circuit/System Verification

Ignition ON, headlamp switch to PARK, just the park lamps should illuminate. Headlamp switch to HEAD, the park lamps and headlamps should illuminate.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement (with RPO SLT)»(ref-277990-S12134823092008012100000) or «Headlamp Switch Replacement (without RPO SLT)»(ref-277990-S21174291342008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Ignition ON, cover the ambient light sensor. Vary the interior lamp dimming switch from dim to full bright. The I/P lamps should dim and then become full bright.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement (with RPO SLT)»(ref-277990-S12134823092008012100000) or «Headlamp Switch Replacement (without RPO SLT)»(ref-277990-S21174291342008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Fog Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, activate the Fog Lamps output control on the scan tool. The Front Fog Lamp Relay Command parameter in the data list should display On and the front fog lamps should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(ref-278007-S05035048592008012100000) or «Relay Replacement (Attached to Wire Harness)»(ref-278007-S22822227782008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, activate the Backup Lamps output control on the scan tool. The Backup Lamps parameter in the data list should display On and the backup lamps should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(ref-278007-S27290193332008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM, inside rearview mirror, and rearview camera module replacement, setup, and programming

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for driver or passenger door switch replacement, setup, and programming

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, activate the Low Beam output control on the scan tool. The Low Beam Relay Command parameter in the data list should display On and the low beam headlamps should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(ref-278007-S05035048592008012100000) or «Relay Replacement (Attached to Wire Harness)»(ref-278007-S22822227782008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, activate the High Beam output control on the scan tool. The High Beam Relay Command parameter in the data list should display On and the high beam headlamps should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(ref-278007-S27290193332008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, activate the Parking Lamp output control on the scan tool. The Park Lamp Relay Command parameter in the data list should display On and the park lamps should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(ref-278007-S05035048592008012100000) or «Relay Replacement (Attached to Wire Harness)»(ref-278007-S22822227782008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Block the drive wheels. Carefully supply sufficient light to simulate daylight conditions to the ambient light sensor. With the engine running, headlamp switch in AUTO, and the park brake released, the DRL should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(ref-278007-S27290193332008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition and park lamps ON, vary the interior lamp dimming switch from dim to full bright. The LED lamps should dim and then become full bright.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Refer to the appropriate replacement procedure for the component causing the condition.
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM, driver door switch, and passenger door switch replacement, setup, and programming

Schematic Reference

Interior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, activate the Courtesy Lamps output control with the scan tool. The interior courtesy lamps should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Refer to the appropriate replacement procedure for the component causing the condition.
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM, driver door switch, and passenger door switch replacement, setup, and programming

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, headlamp switch to PARK, vary the interior lamp dimming switch from dim to full bright. The LED lamps should dim and then become full bright.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Refer to the appropriate replacement procedure for the component causing the condition.
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Ambient Light Sensor Replacement»(ref-277990-S16784669572008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON and park lamps ON, vary the headlamp and panel dimmer switch from dim to full bright. The I/P lamps should dim and then become full bright.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Refer to the appropriate replacement procedure for the component causing the condition.
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, press the brake pedal. The stop lamps should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Tail Lamp Bulb Replacement (Chevrolet)»(ref-277990-S23177271242008012100000) or «Tail Lamp Bulb Replacement (GMC)»(ref-277990-S23959392802008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Ignition ON, headlamp switch to HEAD, vary the interior lamp dimming switch from dim to full bright. The I/P lamps should dim and then become full bright.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Headlamp Switch Replacement (with RPO SLT)»(ref-277990-S12134823092008012100000) or «Headlamp Switch Replacement (without RPO SLT)»(ref-277990-S21174291342008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Ignition ON, press the brake pedal. The CHMSL should illuminate.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Underhood Electrical Center or Junction Block Replacement»(ref-278007-S27290193332008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Symptoms - Lighting

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) , before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to the following: «Exterior Lighting Systems Description and Operation»(ref-277990-S37916934242008012100000) «Interior Lighting Systems Description and Operation»(ref-277990-S41670391962008012100000)

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Backup Lamps Always On

Backup Lamps Always On

Backup Lamps Inoperative

Backup Lamps Inoperative

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Output Controls»(ref-277990-S26654000102008012100000)
2. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
3. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «High Mount Stop Lamp Replacement (Extended and Crew Cab)»(ref-277990-S03962778682008012100000) or «High Mount Stop Lamp Replacement (Regular Cab)»(ref-277990-S25455659852008012100000)
2. «High Mount Stop Lamp Bulb Replacement (GMC Denali)»(ref-277990-S11973855892008012100000)
3. «Underhood Electrical Center or Junction Block Replacement»(ref-278007-S27290193332008012100000)
4. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup and programming

Clearance Lamps Inoperative

Clearance Lamps Inoperative

Courtesy Lamps Always On

Courtesy Lamps Always On

Courtesy Lamps Inoperative

Courtesy Lamps Inoperative

Daytime Running Lamps (DRL) Always On

Daytime Running Lamps (DRL) Always On

Daytime Running Lamps (DRL) Defeat Inoperative

Daytime Running Lamps (DRL) Defeat Inoperative

Daytime Running Lamps (DRL) Inoperative (Z88)

Daytime Running Lamps (DRL) Inoperative (Z88)

Daytime Running Lamps (DRL) Inoperative (X88 and Z75)

Daytime Running Lamps (DRL) Inoperative (X88 and Z75)

Exterior Courtesy Lamp(s) Always On

Exterior Courtesy Lamp(s) Always On

Exterior Courtesy Lamp(s) Inoperative

Exterior Courtesy Lamp(s) Inoperative

Fog Lamp Indicator Inoperative

Fog Lamp Indicator Inoperative

Fog Lamps Always On

Fog Lamps Always On

Fog Lamps Inoperative

Fog Lamps Inoperative

Hazard Lamps Always On

Hazard Lamps Always On

Hazard Lamps Inoperative

Hazard Lamps Inoperative

Headlamp Low or High Beams Always On

Headlamp Low or High Beams Always On

Headlamps Inoperative - High Beams

Headlamps Inoperative - High Beams

Headlamps Inoperative - Low Beams (Standard)

Headlamps Inoperative - Low Beams (Standard)

Low and High Beams Headlamps Inoperative

Low and High Beams Headlamps Inoperative

Headlamps Flash to Pass Inoperative

Headlamps Flash to Pass Inoperative

High Beam Indicator Always On

High Beam Indicator Always On

High Beam Indicator Inoperative

High Beam Indicator Inoperative

Interior Backlighting Does Not Dim

Interior Backlighting Does Not Dim

Interior Backlighting Inoperative

Interior Backlighting Inoperative

Park, License, and Tail Lamps Always On

Park, License, and Tail Lamps Always On

Park, License, and Tail Lamps Inoperative

Park, License, and Tail Lamps Inoperative

Reading Lamp(s) Inoperative

Reading Lamp(s) Inoperative

Roof Beacon Lamp Always On

Roof Beacon Lamp Always On

Roof Beacon Lamp Inoperative

Roof Beacon Lamp Inoperative

Stop Lamps Always On

Stop Lamps Always On

Stop Lamps Inoperative

Stop Lamps Inoperative

Turn Signal Lamps and/or Indicators Always On or Flashing

Turn Signal Lamps and/or Indicators Always On or Flashing

Vanity Mirror Lamp(s) Inoperative

Vanity Mirror Lamp(s) Inoperative

Scheme 67

Stop Lamp Switch Replacement (Non-Adjustable Pedal)

Scheme 68

Stop Lamp Switch Replacement (Adjustable Pedal)

Scheme 69

Headlamp Switch Replacement (with RPO SLT)

Scheme 70

Headlamp Switch Replacement (without RPO SLT)

Headlamp Aiming (Chevrolet/GMC)

Headlamp aiming is done with the low beam lamps. The high beam lamps will be correctly aimed if the low beam lamps are aimed properly.

Screen Method for Headlamp Aiming (Visual Aim)

The screen method requires an area set up specifically for headlamp aim.

The area should consist of a level surface large enough to allow for a vehicle and an additional 7.62 m (25 ft) as measured from the face of the headlamps to the aiming screen.

The screen should be a wall or other flat surface at least 1.52 m (5 ft) high by 3.66 m (12 ft) wide with a matte white surface well shaded from extraneous light, and 90 degrees to the floor. The screen should be provided with a permanent vertical reference line 0.61 m (2 ft) from the left edge of the screen, 2 laterally adjustable vertical tapes, and one vertically adjustable horizontal tape.

After the aiming screen has been set up and located, paint or tape a reference line on the floor 15.24 m (50 ft) from the vertical reference line on the screen. This line should be perpendicular to the aiming screen and a mark placed at 7.62 m (25 ft) from the screen.

Headlamp Aiming Procedure

1. Align the left tires of the vehicle with the reference line extending from the screen with the headlamps aligned with the reference line.
2. Remove any snow, ice or mud from the vehicle.
3. The vehicle should be fully assembled and all other work stopped while the headlamp aiming is being done.
4. The vehicle should contain cargo or be loaded to represent normal vehicle use.
5. Tires should be properly inflated.
6. Rock the vehicle to stabilize the suspension.
7. Measure from the floor to the center of the lamp bulb on the vehicle. Some lamps have an aim dot marked on the lens.
8. At the screen, measure from the floor and place the horizontal tape at the measured distance.
9. Measure from the reference line on the floor to the left headlamp bulb centerline (1).
10. At the screen, measure from the reference line and place the vertical tape at the measured distance (2).
11. Measure from the reference line on the floor to the right headlamp bulb centerline.
12. At the screen, measure from the reference line and place the vertical tape at the measured distance.
13. Turn the headlamps ON.
14. Block the light from projecting onto the screen from the passenger side headlamp. This will allow the cutoff in the beam pattern from the drivers side to be more pronounced for easier aim verification.
15. On this vehicle you will be verifying the aim of the vertical cutoff on the right side of the lamp vertical bulb centerline as it is projected onto the aim board.
16. If the location of the cutoff projected onto the board differs from see scheme 4 then an adjustment to the beam pattern location is necessary.
17. Adjust the vertical headlamp adjustment screw until the Right Gradient Line (Cutoff Line) is set at the Horizontal Axis within +/- 2.0 inches (2) measured at 7.62 m (25 ft).
18. Verify proper aim location.
19. Repeat the aiming procedure for the passengers side headlamp while blocking the light from projecting onto the screen from the drivers side headlamp.

Scheme 71

Front Fog Lamp Replacement (Chevrolet)

Scheme 72

Front Fog Lamp Replacement (GMC)

Scheme 73

Front Fog Lamp Bulb Replacement (Chevrolet)

Scheme 74

Front Fog Lamp Bulb Replacement (GMC)

Fog Lamp Aiming

The front fog lamps must be aimed for proper illumination of the road. The front fog lamp aim should be checked when a new front fog lamp assembly is installed, or if service or repairs in the front end area may have disturbed the front fog lamp mounting.

Preparation Procedure

1. Completely assemble all of the components on the vehicle.
2. Park the vehicle on a level surface.
3. Stop all unnecessary operations or work on the vehicle that affect the vehicle trim.
4. Close the doors and ensure that the vehicle has no load other than the driver.
5. Stabilize the suspension by rocking the vehicle sideways.
6. Ensure that the fuel level is 1/2 full.
7. Ensure that the tires are inflated to the proper pressure.
8. Ensure that the driver or a similar weight, approximately 75 kg (165 lb), is in the vehicle driver seat.

Aiming Procedure

1. Park the vehicle on a level surface 7.6 m (25 ft) (3) away from a wall or other flat surface.
2. Measure the distance from the floor to the center of the fog lamp (5).
3. Using this measurement, mark the horizontal centerline of the fog lamp (1) on the flat surface directly in front of the vehicle.
4. Remove the front portion of the front wheel liner in order to access the adjusting screw.
5. Turn ON the fog lamps.
6. Reach inside of the front portion of the fender liner in order to access the fog lamp vertical adjustment screw on the bottom of the fog lamp.
7. Adjust the fog lamp so that the top edge of the fog lamp beam pattern is 100 mm (4 in) below the horizontal centerline (2).
8. Turn OFF the fog lamps.
9. Secure the forward edge of the front fender liner.

Scheme 75

Front Side Marker Lamp Bulb Replacement (GMC)

Scheme 76

Roof Marker Lamp Replacement (U01)

Scheme 77

Roof Marker Lamp Replacement (U01)

Scheme 78

Rear Side Marker Lamp Replacement (Silverado HD)

Scheme 79

Rear Side Marker Lamp Replacement (GMC HD)

Scheme 80

Park/Turn Signal Lamp Bulb Replacement (Chevrolet)

Scheme 81

Park/Turn Signal Lamp Bulb Replacement (GMC)

Scheme 82

High Mount Stop Lamp Replacement (Extended and Crew Cab)

Scheme 83

High Mount Stop Lamp Replacement (Regular Cab)

Scheme 84

High Mount Stop Lamp Bulb Replacement (GMC Denali)

Scheme 85

Backup Lamp Bulb Replacement (Chevrolet)

Scheme 86

Backup Lamp Bulb Replacement (GMC)

Exterior Lamps

The exterior lighting system consists of the following lamps

1. The headlamps
2. The daytime running lamps (DRL)
3. The front fog lamps
4. The park, tail and marker lamps
5. The exterior courtesy lamps
6. The turn signal/hazard lamps
7. The stop lamps
8. The backup lamps
9. The cargo lamps
10. The roof beacon lamp (if equipped)

Headlamps

The headlamps may be turned on in 2 different ways. First, when the driver places the headlamp switch in the HEADLAMP position, for normal operation. Second, with the headlamp switch placed in the AUTO position, for automatic lamp control (ALC). During ALC the headlamps will be in DRL operation in daylight conditions, or headlamp operation in low light conditions.

Headlamp ON/OFF control is determined by the body control module (BCM) by a signal on the headlamp switch on input circuit when the headlamp switch is in the HEAD position. When the headlamp switch is in the AUTO position, the BCM determines headlamps ON/OFF by the voltage from the ambient light sensor.

If the headlight switch is left in the ON position, the inadvertent power control feature will turn off the headlights approximately 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the headlights will remain on until turned off or the battery runs dead.

The high beam indicator is illuminated when the instrument cluster receives a GMLAN serial data message from the BCM that the high beams are illuminated.

High Beams

The high beam headlamps receive voltage from the headlamp high relay located in the underhood fuse block. The BCM controls the relay on the headlamp high beam relay control circuit. High beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamp dimmer switch signal circuit is grounded, the BCM grounds the headlamp high beam relay control circuit, illuminating the high beam headlamps. The right and left high beam circuits are independent and are fused independently in the underhood fuse block.

Low Beams

The low beam headlamps receive voltage from the headlamp low beam relay located in the underhood fuse block. The BCM controls the relay on the headlamp low beam relay control circuit. Low beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamp dimmer switch signal circuit is open, the BCM grounds the headlamp low beam relay control circuit, illuminating the low beam headlamps. The right and left low beam circuits are independent are fused independently in the underhood fuse block.

Daytime Running Lamps (DRL)

The DRL will only operate while the engine is running and the headlamp switch is in the AUTO position. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will illuminate. The ambient light sensor is a light sensitive transistor that varies its voltage signal to the BCM in response to changes to the outside ambient light level. When the BCM receives this signal it will either turn on the dedicated DRL on the X88, the low beam headlamps only as DRL on the Z88, or the headlamps, park, and tail lamps for auto headlamp operation in low light conditions. Any function or condition that turns on the headlights will cancel the daytime running lamps operation. The DRL can be manually turned OFF by activating the AHL/DRL switch in the headlamp switch. The AHL/DRL defeat switch sends a ground signal through the DRL switch signal circuit to the BCM. The BCM then turns OFF the DRL. When the AHL/DRL are manually turned OFF at the headlamp switch, the AHL/DRL will default to ON with the next ignition cycle. With the headlight switch in the AUTO position, the DRL will either be turned ON or OFF after an approximate 8 second delay, depending on whether daylight or low light conditions are sensed. When the BCM energizes the DRL relay, the DRL receives voltage on the DRL supply voltage circuit.

Fog Lamps

With both the ignition switch in the RUN position, and the park lamps ON, the fog lights will illuminate when the driver depresses the fog lamp switch. The BCM receives the park lamp ON signal from the interior park lamps supply voltage signal circuit. With the headlamp switch in either the park or headlamp position, and the fog lamp switch is in the ON position, the BCM will ground the fog lamp relay control circuit causing the relay to energize. The current flows from the fog lamp relay to both front fog lamps. The state of the fog lamps will remain the same until the fog lamp switch position is changed, or the ignition switch is cycled OFF and ON. Fog lamp operation will be cancelled whenever the park lamps, are turned OFF or the high beam headlights have been selected.

Park, Tail and Marker Lamps

The park, tail and marker lamps, including the license lamps, are turned on when the headlamp switch is placed in the PARK or HEAD position or anytime the headlights are requested. The underhood fuse block supplies battery positive voltage to both the park lamp relay switch contacts and the park lamp coil circuit. The BCM provides a ground or control circuit to the park lamp relay coil circuit. When the park lamps are turned ON, the BCM energizes the park lamp relay. If the headlight switch is left in the ON position, the inadvertent power control feature will turn OFF the park, tail and marker lamps approximately 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the park, tail and marker lamps will remain on until turned OFF or the battery runs dead.

Exterior Courtesy Lamps

The BCM, driver door switch, and the passenger door switch communicate through the GMLAN serial data system. The driver door switch and passenger door switch supply power and ground to the left and right exterior lamps respectively. When the BCM commands illuminated entry, a command is also sent to the door switches for illumination of the exterior courtesy lamps. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either the ON or RUN position the exterior courtesy lamps will deactivate immediately.

Turn Signal/Hazard Lamps

When the turn signal switch is placed in either the left or right position, a ground signal is completed from the turn signal switch to the BCM. When the hazard flasher switch is activated, a ground signal is completed from the turn signal/hazard switch to the BCM. The BCM then sends an ON-OFF voltage signal through the fuses to the appropriate turn signal and side repeater (export only) lamps or to all of the turn signal fuses for hazard operation. The driver door switch and passenger door switch also receive voltage from the BCM turn signal supply voltage circuits for the mirror turn signals. The door switches have no function or control of the mirror turn signals other than a pass through connection for the circuits. The audio chime is also activated when the turn signals are ON. The instrument panel cluster (IPC) receives the signals to activate the turn signal indicators over the GMLAN serial data system. When the hazard switch is pressed, all turn signal lamps will flash including both IPC turn indicators.

Stop Lamps

When the driver presses the brake pedal, the switch contacts open and battery positive voltage is interrupted to the BCM. The BCM then supplies voltage to both the turn/stop lamp supply voltage circuit and trailer rear turn/stop lamp supply voltage circuits. The BCM also supplies a control voltage to the CHMSL relay energizing the relay and illuminating the CHMSL.

Backup Lamps

The backup lamp request signal is sent from the PCM to the BCM on the GMLAN serial data system. This signal is based on the park neutral position (PNP) switch signal. The BCM supplies voltage to the backup relay and to the automatic day/night mirror when the vehicle is in reverse. The backup relay supplies a voltage on the backup lamp supply voltage circuit to the backup lamps and trailer backup circuit.

Cargo Lamps

The cargo lamp is controlled by the courtesy lamp supply voltage circuit. The BCM supplies voltage to the cargo lamp anytime courtesy lamp activation is requested.

Clearance Lamps

The clearance lamps, are turned ON when the headlamp switch is placed in the PARK or HEAD position or anytime the headlamps are requested. The underhood fuse block supplies battery positive voltage to both the park lamp relay switch contacts and the park lamp coil circuit. The BCM provides a ground or control circuit to the park lamps relay coil circuit. When the park lamps are turned ON, the BCM energizes the park lamp relay. If the headlamp switch is left in the ON position, the inadvertent power control feature will turn OFF the park, tail and clearance lamps approximately 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlamp switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the park, tail and marker lamps will remain ON until turned OFF or the battery runs dead.

Interior Lamps

The interior lighting consists of 2 groups. The first group includes lamps that may not be dimmed.

1. Courtesy/illuminated entry lamps
2. Dome lamps
3. Map lamps
4. Reading lamps
5. Vanity mirror lamps

Courtesy/Illuminated Entry Lamps

The courtesy/illuminated entry lamps, may be manually turned ON or OFF by placing the interior lamp switch in the ON or OFF position. If an outside door handle is lifted and a door is opened, the courtesy/illuminated entry lamps illuminate. After all the doors have been closed the courtesy/illuminated entry lamps will remain illuminated approximately 15 seconds. The body control module (BCM) will then turn them OFF through the theater dimming feature. The courtesy/illuminated entry lamps will also turn ON prior to any door being opened, and remain illuminated approximately 40 seconds when the driver removes the ignition key. When the driver places the dome lamp defeat switch in the OFF position, the courtesy/illuminated entry lamps will be disabled.

The BCM and the door modules communicate through the GMLAN serial data circuit for the lamp illumination commands of the door switch signals. The left and right rear door latch switches are both on one circuit that is also an input to the BCM.

The left and right front door courtesy lamps (if equipped) receive voltage and ground from the driver door switch and the passenger door switch respectively. The remaining courtesy lamps are controlled and receive voltage from the BCM. Voltage for the courtesy lamp supply voltage circuit is from the INT LTS fuse in the instrument panel fuse block.

Keyless Entry Interior Illumination

When the driver uses the door key in order to unlock the doors, the body control module (BCM) receives a door unlock signal. The BCM must have inputs or serial data messages that indicate that the ignition switch is OFF, the courtesy lamp switch is OFF and all the doors are closed. The BCM will then activate the interior lamps. The courtesy lamps will remain ON, approximately 15 seconds after the door is closed. The BCM will then turn them OFF through the theater dimming feature. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either the RUN or CRANK position the courtesy lamps will turn OFF immediately.

When the driver uses the remote function actuator transmitter to unlock the doors, trunk or presses the panic button, the BCM will keep the courtesy lamps ON approximately 40 seconds. When the driver uses the remote function actuator transmitter to lock the doors, the BCM will keep the courtesy lamps on approximately 2 seconds. If the ignition switch is turned to either the RUN or CRANK position the courtesy lamps will turn OFF immediately.

Vanity Lamps

The inadvertent power supply voltage circuit of the body control module (BCM) provides battery positive voltage to each vanity mirror lamp. When the vanity mirror cover on the sunshade is opened, a switch closes to provide a ground circuit and the vanity lamp illuminates.

Reading Lamps

The inadvertent power supply voltage circuit of the body control module (BCM) provides battery positive voltage to the reading lamps. The reading lamps and switch are integral to the courtesy/reading lamp assembly. When the switch is closed, voltage is supplied and the lamp illuminates.

Battery Rundown Protection/Inadvertent Power

The body control module (BCM) inadvertent power supply voltage circuit provides battery positive voltage to all of the interior reading lamps, visor vanity mirror lamps, and cargo lamps if equipped. In the event that any of these lamps were to remain illuminated for a period of more than 10 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge condition.

Interior Lamps Dimming

The second interior lighting group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination, LED illumination and incandescent lamps.

When the ignition switch is turned to the RUN position, the radio VF display turns ON at maximum brightness. When the park lamps are ON, all incandescent and LED back lighting turn ON at the dimming level indicated by the instrument panel (I/P) dimmer switch. At the same time all VF displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the body control module (BCM). When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. When the I/P dimmer switch is moved from MIN to MAX, all VF displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the I/P dimmer switch.

The following switches and components have back lighting when the park lamps are ON

1. The instrument panel cluster (IPC)
2. Window and heated seat switches
3. Rear HVAC switches
4. Sunroof switch
5. Accessory switches
6. Fog lamp switches
7. Garage door opener
8. Rear parking assist (RPA) disable switches
9. Transfer case shift control switch
10. Power take off switch
11. Roof beacon switch
12. Sliding rear window switch
13. PRNDL lamps
14. Traction control switch
15. Steering wheel control switches
16. Integrated trailer brake controller switch

The left and right front door switch illumination is controlled, receives voltage and ground from the driver door switch and passenger switch respectively. The radio is also a GMLAN module and has full control of its illumination. The BCM, door switches, and radio communicate through GMLAN serial data for the lamp illumination commands.

The various switches, HVAC control assembly, and the PRNDL lamps receive voltage and are controlled by the BCM on the I/P lamps dimming control circuit.

The following indicators receive voltage from the BCM and are controlled by ground from a switch or from various modules

1. Tow indicator
2. Transfer case control switch 4WD position indicators
3. Fog lamp indicators
4. Radio
5. Analog clock
6. HVAC control assembly
7. Instrument panel cluster (IPC)
8. Driver information center (DIC)
9. Headlamp and panel dimmer switch
10. Rear parking assist (RPA) indicator

The indicators receive voltage from the BCM on the LED dimming circuit. Control for the indicators is from the various modules or switches. Voltage for the LED dimming supply circuit, instrument panel lamps dimming control circuit and the instrument panel lamps dimming supply circuit is from the BCM.

The modules controlling the above indicators are as follows

1. Transfer case shift control module
2. BCM