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 , Computer/Integrating Systems Connector End Views in Computer/Integrating Systems, or Power Door Systems Connector End Views in Doors

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the headlamp switch in the PARK position.
  3. Cover the ambient light sensor.
  4. Turn the instrument panel (I/P) dimmer switch from minimum to maximum intensity.

Do the interior backlighting lamps operate properly?

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

Go to Step 3

3

Are the interior backlighting lamps always ON?

Go to Step 5

Go to Step 4

4

  1. Install a scan tool.
  2. With a scan tool, observe the Interior Dim Pot parameter in the instrument panel integration module (IPM) open/short data list.
  3. Turn the I/P dimmer switch from minimum to maximum intensity.

Does the scan tool indicate that the Interior Dim Pot parameter is changing when the I/P dimmer switch is turned?

Go to Step 6

Go to Step 7

5

Test the backlight lamps control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 6

6

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

Did you complete the replacement?

Go to Step 8

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7

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 8

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8

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2