For 1990-2009 cars

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 to observe the Dimming Potentiometer voltage data in the body control module (BCM) Data List while adjusting the dimmer switch throughout the full range. Does the scan tool data indicate an approximate voltage change from the minimum to the maximum voltage? | Go to Step 6 | Go to Step 4
4 | Test for a short to ground in the instrument panel lamps dimming signal circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct a condition? | Go to Step 9 | Go to Step 5
5 | Inspect for poor connections at the harness connector of the headlamp and panel dimmer switch. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 7
6 | Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 8
7 | Replace the headlamp and panel dimmer switch. Refer to Headlamp Switch Replacement . Did you complete the replacement? | Go to Step 9 | --
8 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | --
9 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3