Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 533 (LIGHTING SYSTEMS)DIAGNOSTIC INFORMATION AND PROCEDURESCOURTESY LAMPS INOPERATIVE
1999 GMC Forward Control 5.7 R, Automatic
Courtesy Lamps Inoperative
1999 GMC Forward Control 5.7 R, AutomaticSECTION Courtesy Lamps Inoperative
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
Courtesy Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems. |
|||
| 1 | Did you perform the Lighting System Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Lighting Systems |
| 2 |
|
Go to Step 3 | Go to Step 4 |
| 3 | Open and close each door and the lift gate. Do the courtesy lamps turn ON when you open each door and the lift gate? |
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 5 |
| 4 | Are all of the courtesy lamps inoperative? | Go to Step 7 | Go to Step 12 |
| 5 | Test the door open circuits for a high resistance, an open, or a short to battery positive voltage. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 6 |
| 6 | Test the ground circuit of the door latch assembly for a high resistance or an open. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 11 |
| 7 |
|
Go to Step 13 | Go to Step 8 |
| 8 | Inspect for an open or a short to battery positive voltage in the switched dome circuit. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 9 |
| 9 | Test for an open, short to ground or a short to battery positive voltage in the courtesy lamps control circuit. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 10 |
| 10 | Inspect for a poor connection at the harness connection of the Body Control Module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 15 |
| 11 | Inspect for a poor connection at the harness connection of the inoperative door latch assembly. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 16 | Go to Step 14 |
| 12 | Repair the open in the inoperative courtesy lamp power supply voltage circuit or courtesy lamps control circuit. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you complete the repair? |
Go to Step 16 | - |
| 13 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the replacement? |
Go to Step 16 | - |
| 14 |
IMPORTANT:
Perform the setup procedures for the Body Control Module (BCM). Refer to Body Control Module (BCM) Programming/RPO Configuration
. Replace the inoperative door latch assembly. Refer to Lock Replacement - Front Door
or Lock Replacement - Rear Door
in Doors or Latch Replacement - Liftgate (Aztek)
in Body Rear End.Did you complete the replacement? |
Go to Step 16 | - |
| 15 | Replace the BCM. Refer to Body Control Module Replacement
in Body Control System. Did you complete the replacement? |
Go to Step 16 | - |
| 16 | Operate the system in order to verify the repair. Did you correct the condition? |
System OK | Go to Step 3 |
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.