GM Repair Problems? Ask GM Repair Expert Now.
This circuit is difficult to diagnose without a scantool because you need to use it to see if the BCM is commanding the DRL or not, if it is and they light aren't on, the trucks in drive and the parking brake is not applied, engine running and DRL FUSE is good, you more than likely have a bad under hood fuse block. The DRL relay is built in the circuit board of the fuse block. Other than that if the BCM data shows its not commanding DRL on you need to see if it show the headlight switch in auto position. Also you'll need to see if the light sensor voltage data change when light and darkness hit the sensor. Please give a positive rating. I hope this helps. Thanks