GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics or Body Control System Schematics in Computer/Integrating Systems

Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Verify that the interior backlighting is inoperative.

Does the interior backlighting operate normally?

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

Go to Step 3

3

Are all of the interior backlighting lamps inoperative?

Go to Step 5

Go to Step 4

4

Test for an open or high resistance in the following circuits of the inoperative lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

    • The instrument panel lamps dimming control
    •  The LED dimming supply
    • The ground

Did you find and correct a condition?

Go to Step 13

Go to Step 8

5

Is the TBC 2A Fuse in the instrument panel (I/P) fuse block open?

Go to Step 6

Go to Step 7

6

Test the battery positive voltage circuit of the body control module (BCM) for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 10

7

Test for the following conditions. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

    • Short to voltage in the dimmer potentiometer low reference circuit of the BCM.
    • High resistance or an open in the LED dimming signal circuit of the BCM.
    • Short to ground in the LED dimming signal circuit of the BCM.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

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

Did you find and correct the condition?

Go to Step 13

Go to Step 11

9

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

Did you find and correct the condition?

Go to Step 13

Go to Step 12

10

Repair the controls illumination lamps dimming control circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

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11

Replace the affected lamp or internal lamp component.

Did you complete the replacement?

Go to Step 13

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12

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 13

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13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3