GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Interior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System

1

Did you perform the Lighting Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Verify that the courtesy lamps are always on.

Do the courtesy lamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Disconnect the courtesy lamp relay from the body relay block.

Did the courtesy lamps remain illuminated?

Go to Step 10

Go to Step 4

4

Inspect for the following related BCM data parameters as applicable. Refer to Scan Tool Data List and Scan Tool Data Definitions for typical values and definitions:

    • The dome lamp switch
    • The dome override switch
    • The passenger door jamb/door handle switches
    • The driver door jamb switch
    • The rear door ajar
    • The liftglass/rear gate

Was a problem found?

Go to Step 6

Go to Step 5

5

Test the courtesy lamp relay control circuit for a ground signal at the relay socket. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Was a ground signal present?

Go to Step 9

Go to Step 12

6

Disconnect and test the switch of the affected input circuit for proper continuity in the open and closed positions. Refer to Circuit Testing in Wiring Systems.

Does the switch operate properly?

Go to Step 7

Go to Step 8

7

Test the signal and ground circuits of the affected input circuit for a short to ground, open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 9

8

Inspect for poor connections at the harness connector of the affected switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

9

Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 13

10

Repair the short to ground in the courtesy lamp low control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

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11

Replace the switch in the affected circuit. Refer to one of the following replacement procedures as applicable:

    •  Endgate Window Latch Replacement in Body Rear End

Did you complete the replacement?

Go to Step 14

--

12

Replace the courtesy lamp relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the repair?

Go to Step 14

--

13

Important: Perform the setup procedure for the BCM.

Replace the body control module (BCM). Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 14

--

14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3