GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics or Body Control System Schematics

Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Verify that the interior backlighting is inoperative.

Does the interior backlighting operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

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 .

    • 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 .

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 .

    • 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 .

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 .

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 .

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 .

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