Test Description
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
5. Tests for voltage at the LED dimming signal circuit.
6. Tests for a BCM output to the headlamp switch.
7. Determines if it is the headlamp on indicator circuit or the BCM.
8. After replacement of the BCM you must calibrate the new module for proper operation.