Circuit/System Testing

WARNING: This page is about a different car, the 2007 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.

I/P Dimmer Switch Malfunction

Ignition OFF, disconnect the harness connector at the I/P Dimmer switch.
Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 10.
- If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
Ignition ON, test for B+ between the I/P dimming voltage reference circuit terminal 5 and ground.
- If less than the specified range, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- If greater than the specified range, test the voltage reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.
Install a 3-A fused jumper wire between the signal circuit terminal 9 and the B+ voltage reference circuit terminal 5. Verify the scan tool dimming control signal parameter is greater than 2.5 volts.
- If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
If all circuits test normal, test or replace the I/P dimmer switch.

I/P Dimming Control Malfunction

Ignition OFF, disconnect the C3 harness connector at the BCM.
Ignition ON, verify that a test lamp illuminates between the BCM 1 fuse voltage supply circuit terminal 3 and ground.
- If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance.
If all circuit tests normal, replace the BCM.