Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the affected component.
- Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and battery voltage.
- Headlamp Switch terminal 8
- Sunroof switch terminal 5
- Front door lock switch w/o AN3 terminal B
- Driver window switch w/o AN3 terminal A X2
- Front passenger window switch w/o AN3 terminal F
- OSRVM switch w/o AN3 terminal G
- Transfer case shift control switch terminal 6
- Roof beacon switch terminal 1
- Sliding rear window switch terminal D
- Rear window switch terminal F
- If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
- Connect a test lamp between the listed backlighting control circuit terminal and ground.
- Headlamp Switch terminal 7
- Sunroof switch terminal 3
- Front door lock switch w/o AN3 terminal A
- Driver window switch w/o AN3 terminal 1 X1
- Front passenger window switch w/o AN3 terminal B
- OSRVM switch w/o AN3 terminal E
- Transfer case shift control switch terminal 5
- Roof beacon switch terminal 2
- Sliding rear window switch terminal E
- Rear window switch terminal B
- Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
- If the test lamp is always off, test the control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.
- If the test lamp is always bright, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If all circuits test normal, test or replace the affected component.