Circuit/System Testing
WARNING: This page is about a different car, the 2006 Buick Lucerne. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the DRL Relay from the rear fuse block.
- Ignition ON, headlamps OFF, verify that a test lamp does not illuminate between the supply voltage circuit terminal 94 and ground.
- If the test lamp illuminates, test the low beam supply voltage circuit for a short to voltage.
- Verify that a test lamp illuminates between the B+ circuit terminal 90 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Verify that a test lamp illuminates between the B+ circuit terminal 93 and ground.
- If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
- Connect a test lamp between the B+ circuit terminal 90 and the control circuit terminal 92.
- Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
- Headlamps OFF, connect a 3A fused jumper wire between the B+ circuit terminal 93 and the supply voltage circuit terminal 92. The low beam headlamps should illuminate.
- If the headlamps do not illuminate, test the supply voltage circuit for an open/high resistance. If the circuit tests normal, test or replace the DRL fuse or the rear fuse block.
- If all circuits test normal, test or replace the DRL relay.