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 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 does not dim.

Does the interior backlighting operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Use the scan tool output controls to operate the interior backlighting.

Can you control the dimming level of an activated control switch indicator with the scan tool?

Go to Step 4

Go to Step 5

4

Test for an open, high resistance, short to voltage, or short to ground in the following circuits. Refer to Circuit Testing and Wiring Repairs .

    • The 12-volt reference
    • The instrument panel lamp dimmer switch signal
    • The indicator dimming control
    • The instrument panel lamp dimming control

Did you find and correct a condition?

Go to Step 10

Go to Step 6

5

Test for a short to voltage in the LED dimming circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct a condition?

Go to Step 10

Go to Step 7

6

Inspect for poor connections at the harness connector of the headlamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 9

8

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 10

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9

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3