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 or short to ground in the following circuits. Refer to Circuit Testing and Wiring Repairs.

    • The 5-volt reference
    • The dimming input
    • The dimming return

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 Circuit Testing and Wiring 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 Circuit Testing and Wiring 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

--

9

Replace the BCM. Refer to Control Module References.

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