revvychevy
Newbie
Hey guys, my first time here. Bought a 1995 GMC 3500 a few months ago and all has worked fine up till last night. Had just been driving the truck with the lights on, stopped at a buddy’s house and turned it off for maybe an hour. I started it to leave and guess what. The headlights that had been working fine an hour ago won’t turn on. I turned the switch and nothing. Tried the high beams and they didn’t work either. I got it home and got the volt meter out to do some testing. Often the switches go bad so I pulled the plug on the light switch and jumped the wires for the headlights. Nothing. So that rules out the switch on the dashboard. Hooked the switch back up, tapped into the green and tan headlight wires where they run along the left fender and turned the switch on. They’re both getting 12+ volts when their respective switches are turned on. The truck is running HID’s so I jumped them right to the battery and they turn on, eliminating four HID systems that could’ve simultaneously quit (it’s happened). I figured it might be the low voltage issue that many of these trucks have, which would run halogen bulbs dimly but not HID’s, so then I took some normal 9005 and 6 halogen bulbs and plugged them into the sockets. They didn’t work either. I decided to test the headlight sockets themselves for voltage and, guess what...nothing at all. Checked the ground wires from the sockets with a resistance test to make sure they’re good and they are.
I did the low beam bypass with a relay so that the low beams stay on with the highs a while ago and it’s worked great. We figured maybe the relay or a connection there is bad. Checked and double checked everything with a volt meter, even the relay socket and connections, and everything works fine, eliminating that as a potential problem.
At this point all I can think of is that maybe since its mischief night, somebody cut my headlight wires somewhere between the fender and the headlight socket. It seems like that’s where the current stops traveling to the headlight socket. But a buddy suggested a resistance test on the wires as a last resort, so we tried that. The high beam wire is good. It turned out the low beam wire has no continuity from the socket to a spot near the cab where I could access it. However...the low beam DOES get continuity between the low beam socket and the high beam wire. Which indicates they’re shorted together somewhere. I checked as much as I could see along the wiring harness and don’t see anywhere it looks like the wires are broken or shorted.
Is there something else I’m not thinking of that this could be? Has anyone had this problem or a similar issue with the headlights too? I’ve heard of the headlights on these trucks shutting off randomly and it seems to always be an issue with the switch. Apparently not in this case.
Thanks for your help!! Sorry for the long read. I tried to list all the info I have. Your answers are much appreciated. Have a happy Halloween
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I did the low beam bypass with a relay so that the low beams stay on with the highs a while ago and it’s worked great. We figured maybe the relay or a connection there is bad. Checked and double checked everything with a volt meter, even the relay socket and connections, and everything works fine, eliminating that as a potential problem.
At this point all I can think of is that maybe since its mischief night, somebody cut my headlight wires somewhere between the fender and the headlight socket. It seems like that’s where the current stops traveling to the headlight socket. But a buddy suggested a resistance test on the wires as a last resort, so we tried that. The high beam wire is good. It turned out the low beam wire has no continuity from the socket to a spot near the cab where I could access it. However...the low beam DOES get continuity between the low beam socket and the high beam wire. Which indicates they’re shorted together somewhere. I checked as much as I could see along the wiring harness and don’t see anywhere it looks like the wires are broken or shorted.
Is there something else I’m not thinking of that this could be? Has anyone had this problem or a similar issue with the headlights too? I’ve heard of the headlights on these trucks shutting off randomly and it seems to always be an issue with the switch. Apparently not in this case.
Thanks for your help!! Sorry for the long read. I tried to list all the info I have. Your answers are much appreciated. Have a happy Halloween
Sent from my iPhone using Tapatalk