1995 GMC headlight buzzer

could be the light switch or if it has a light control module a faulty module

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I have done one on a 1994 Astro, but this video shows a different set of circumstances. I have also linked a reliable parts source that I have used for years.

Its a fuse in the fuse box it should be labeled.
The headlights are switched by a sensor either back of the mirror or on dash.

Bad Headlight switch I put 2 used ones in my 94 Z71 they eventually did the same before I bought a new one which has finally cured the problem.

I would start by checking/cleaning the connections in the headlight circuit. Poor connections will create resistance in the circuit, causing heat which can melt wiring and connectors. Hope this helps!

theres 2 black headlight retainers that u pull up from inside under hood compartment,headlight housing will come out and bulbs will be accessible.

If you have tilt stearing, lower the stearing wheel. Carefully remove the dash trim around the instrument panel and radio a/c controls. Unplug the headlight and truck bed light switches. Lay the trim panel aside. On the side of the control module gently slide a flat screwdriver in the slot until the clip disengages. (Look at the new one to see which way the clips face.) Repeat on other side. Disconnect wire harness plugs. Assembly for the new module is the reverse of the above. Be careful to use gentle pressure on the dash trim or it may break.

Sounds like you either have a bad headlight switch or a bad relay under the hood. Also you might want to try turning the lights on for a minute without the motor running,if they work with motor off then its probably the headlight switch.

Have you checked that the headlight switch is in the right position? Are the headlights or parking lights still on when the key is removed?

If so, then rotate the lamp switch to the correct position and the buzzer will go off. Headlights and parking lights are not controlled through the key circuits.

This is a pretty strait forward process but if you have never done it take it somewhere and ask them to show you how If you turn the adjustment screws it will be out of alignment or they will strip and your headlight alignment will never be right. You could also purchase a chilton or haynes manual for about $20 and it should be covered. You can get these at any parts store