What could cause intermittent headlights on a 2005 GMC Envoy?

[jenny42203]

I have a 2005 GMC Envoy. Recently while driving at night, they both turn off. This has happened to me quite often in the past week. I have had to ride the rest of the way to my destination with my high-beams. However, my fog lights still work.

I have replaced the fuses for both headlights and checked the battery, in case a cable was loose.

It turned off on me when the car was on but in park. It has come back on for me once. This was after I hit the top of the fuse box cover to lock it back in place and the lights immediately turned on.

Could anyone tell me what else to check for?

 

[Molson02536]

I have a 2005 GMC Envoy. Recently while driving at night, they both turn off. This has happened to me quite often in the past week. I have had to ride the rest of the way to my destination with my high-beams. However, my fog lights still work.

I have replaced the fuses for both headlights and checked the battery, in case a cable was loose.

It turned off on me when the car was on but in park. It has come back on for me once. This was after I hit the top of the fuse box cover to lock it back in place and the lights immediately turned on.

Could anyone tell me what else to check for?

Try temporarily swapping #45 Cooling Fan relay and and #46 HDM relay in the under-hood fuse block, and see if the low beams come on.

The one originally in the HDM #46 socket is bad. That relay is actually is a solid state module, not a conventional relay, and will cost you anywhere from $25-45 at the dealer.

HDM = Headlight Driver Module

Also known as a solid-state relay, since instead of relay contacts and a coil, it uses a power switching transistor capable of running the headlights (and the fan clutch in #45) at less than 100% power, to provide daytime running lights, and control the fan clutch engagement for the engine cooling fan.