Need to replace low beam bulbs in 2004 GMC envoy. Help?

Before you replace the #46 HDM relay (in the fuse block under the hood) try exchanging it with the #45 cooling fan relay and see if your low beam lights work. If they do, the HDM relay (actually solid state module, not a relay) is bad.

The switch itself.

It's the headlamp relay #46. If you want to test it, swap it out with the cooling fan relay #45 and see if your headlights work. If they do you know this is the fix. Found the solution online a couple of years ago and it was spot-on. The part was $45 at autozone at the time.

Headlight Replacement (Envoy)

Lift hood, at top of each headlight assembly look for two L-shaped tabs. Pull these tabs straight up, this will release the headlight assembly. Lift assembly forward to gain access to rear of assembly. There two rubber caps, the top one is for access to the low beam and the bottom for the high beam bulbs. Remove the appropriate cap, grasp bulb socket and turn CCW to release. Unplug bulb from socket by releasing catch on side of socket, install new bulb, DO NOT touch bulb glass with fingers. Reverse steps to re-assemble.

Other possibilities are; the bulbs themselves, burnt or corroded bulb sockets, or a bad headlight selector switch.

If you have checked and discounted the relay, the only things left are the headlight switch and the wiring and to the headlights. Try the switch first. It is not impossible that both bulb's low beam filaments may have fused at the same time, unlikely but not impossibly. (It will not be fuses, unless two fuses blew together).

Relay in fuse box under hood on driver side wheel well labeled HDM, #46 on 2004 Envoy XUV. Swap with relay #45 labeled "Fan" to test. That was my problem.

Good Luck,
Sam

Replace relay #46 in the under hood fuse panel, and check fuses #3 and #6 in the same panel.

Just above the headlight assembly are two angled tabs, pull these straight up (they may need some effort). These will release the assembly, carefully pull the entire assembly forward. Access to the headlight bulb is behind the two rubber caps, the upper cap is for the low beam. Remove this cap, twist the headlight bulb socket CCW and remove. Disconnect bulb from harness by prying up gently on locking tab on socket, and pull bulb out. Being careful not to touch the new bulb glass surface with your finger, plug it into the socket and install it back into the headlight assembly turning it CW. Reinstall rubber cap, seat headlight assembly on frame, lining up the bottom and top pegs. Once the assembly is fully seated, push the two angled tabs down, locking the assembly in place.

head light switch