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2002 Silverado No low beam follow up No ground to lowbeams

Hello again So heres the deal (NO Ground to low beams) I went out with my multimeter in hand today and found that the headlights have no ground on the lowbeams now my most logical thought was to just splice in a new ground, so I figured the highbeam ground was very close so why not use that (Right?) Wrong I was then suprised to learn that when I spliced into the high beam ground wire and tried the lowbeams all the headlights now came on high and low beams . So I figured that the grounds must run through a relay of some sort at this point so I disconnected the splice I made and it is back to a no headlight on low beams. But here is my question can I just run a new ground wire spliced into the lowbeam ground wire and ground it to the body of truck (because lowbeams will work when grounded to the body I tested it and yes they worked as they should (but I thought the wire I was using got a lil hot so I did not leave it connected to long). Or are these headlights designed by GM to be grounded only through a relay to avoid burnout? Or can I go ahaed and just use the spliced in ground and use the low beams safely the way the new ground is? Thanks again for all who respond

Reply to
imatoolman
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I have tracked the problem to the low beam ground But can not for the life of me trace the ground back to it point of oringin. I was wondering if I could just jump in a new ground off the frame of the truck? I did a test wiring for a temp ground wire and the headlights worked fine I am just nervous about jumping in a direct ground just in case like you said there is 1/2 voltage involved. But when I placed a volt meter to the positive lead to the bulb and then ground the other lead to the frame and I did get 11.79 volts (12v lets say correct) I can not see why I can not just replce the ground wire at this point I would cut the old wire and install a new ground and see what happens \ any ideas Thanks again

Reply to
imatoolman

You would have that scenario without a ground.

I don't know if that is switched by the ground, but if you have that voltage at both bulbs. It would be indicative of a bad ground.

I sincerely doubt that you'll hurt anything by momentarily touching a ground, to see if the lights work.

If they do, leave the ground >> Hello again So heres the deal (NO Ground to low beams)

Reply to
Refinish King

most likely combination switch chould have no problem makeing a ground at the lights i have done it a couple of times and had no problems

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Reply to
chevyman84

I've pulled up the schematics in GM-SI, and will describe the circuit. The headlights are hot all the time, fed through 2 fuses in the underhood fuse block, one for high beams, and one for low beams. The common side of the dimmer switch is grounded. When switched to low beam, the ground is routed to the underhood fuse block and out through what appears to be a jumper, then to the low beam filament. Ditto for high beams. You know the ground is good, becausse you have high beams. That leaves:

  1. The dimmer switch.
  2. The wire from that to the underhood junction block.
  3. The jumper in the underhood junction block.
  4. The wires from the underhood junction block to the low beam filaments of the 2 bulbs.

KenG

Reply to
KENG

You shouldn't have a ground at either high or low. That truck uses a ground switched system. The dimmer and light switches both complete the circuit by turning on a relay that grounds the correct lights. since the lights come on when you ground them the hot side is OK. Check the low beam relay and it's wiring. Also look at the dimmer switch itself.

Reply to
Steve W.

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