GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hi there, I am Cam. With yourEnvoy, your right to look at the HDM, usually its the issue. As long as your are certain you replaced the HDM and not the driver module for the fan as they are back to back. IF so then let me ask, do the high beams operate properly when cycling them on and off, and when you go to low, the low beams are simply out?
Ok, are you able to do some testing?
I have the diagnostic for this issue. Its attached. If you can follow through it, you should find the issue. I am thinking a wiring issue, switch issue or BCM issue. Also the wiring is included.
Honestly those should. The only thing else I can add is to manually ground the 2 wires, one at a time at the multifunction switch to see if the headlight dimmer switch is bad.