GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics

Connector End View Reference: Lighting Systems 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 indicator dimming control
    • The ground

Did you find and correct a condition?

Go to Step 13

Go to Step 8

5

Are any of the body control module supply voltage fuses open?

Go to Step 6

Go to Step 7

6

Test the affected battery positive voltage supply circuit to 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 a short to ground, open, or high resistance in one of the following circuits. Refer to Circuit Testing and Wiring Repairs .

    • The instrument panel lamps dimming control
    •  The LED dimming supply
    • The indicator dimming control
    • The headlamp and panel dimmer 12-volt reference
    • The headlamp and panel dimmer instrument panel lamps dimmer switch signal
    • The headlamp and panel dimmer switch ground

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 short to ground in one of the following circuits. Refer to Wiring Repairs .

    • The instrument panel lamps dimming control
    •  The LED dimming supply
    • The indicator dimming control
    • The headlamp and panel dimmer 12 volt reference

Did you complete the repair?

Go to Step 13

--

11

Replace the affected lamp or internal lamp component.

Did you complete the replacement?

Go to Step 13

--

12

Replace the BCM. Refer to Control Module References for BCM 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