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no Low beams

SilveradoMike

By SilveradoMike
in Ask A GM Technician

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SilveradoMike Enthusiast

SilveradoMike

Posted
Posted

hi guys,

I have a 02 silverado ext cab. there was a nasty rain storm up here in new england and I hit a rather big puddle on my way home this afternoon and thought nothing of it as it is almost the norm on that raod, well after 3 hours at home I was going to run an errand and found that my lowbeams will not come on. the automatic system turns on my marker lights and my fog lights even come on but no low beams, my highbeams work fine though.

 

I tried to turn them on normally and still nothing I set and released my park break to see if that function may have been stuck but no matter what I do I cant get my lowbeams to work.

I checked the hazard fuse in the under hood fuse box as that was the only one I found that could have blown.

 

everything works the blinkers the horn the hazard light and the high beams.

 

Could I have blown the relay? that was the one thing I didnt look at becasue I'm not sure how they work.

 

Any info would be great!

 

Mike

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted

It wouldn't be fuses or the relay, since both the high beams and low beams get their power from the same source. If it was fuses/relay, you wouldn't have high beams.

 

The lights are controlled by the dimmer switch providing ground to the appropriate lights. The puddle may have had nothing to do with this and is just a coincidence.

 

I'd first go right to the dimmer switch and ground the yellow wire (headlight switch should be ON). If the dimmer is the problem, your low beams will come on when you ground that wire. If they don't, you'll have go step by step to see at what point you have an open in that circuit.

 

The most common problem I've seen is in the connector for that circuit in the UBEC (underhood fuse box). The box rotates up pretty easily once you've removed a few things and you can get a glimpse at that wire in the connector. If it looks like it has been overheated, that's your problem. Seen this more than once.

SilveradoMike Enthusiast

SilveradoMike

Posted
  • Author
Posted

come to find out it was just the bulbs..

very wierd but I tested for power and ground at the connector and they were both there. then tested a bulb for resistance and it was dead. but the fillament was intact. in the second bulb it was cooked.

swapped out the bulbs and am now good to go. I diid look at the wiring too and it seemed all good.

 

very wierd if you ask me.

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted

Having both bulbs burned out at the same time has sent more than one tech on a diagnostic mission and a lot of wasted time!

  • 1 year later...
92__silverado New Member

92__silverado

Posted
Posted

have a 1992 2wd 5spd silverado with a 5.7.

 

Lately my low beam headlights have been going on and off as they please. I thought it was a wireing problem but went over the wires and cannot find anything, then the probem stopped for well over a two weeks. Well last night the problem persisted I bought a new rocker switch which did not fix the problem. I am headed out now with a multimeter to try and test and find a bad ground or any problem. Would a relay cause me to have parking lights, high beams but no lows? Any help would be greatly appreciated. Also when i disconnect the harness from the low beam bulb i get continuity but no voltage, I do not know if I am suppose to get volatge or not but there is none there, if that helps. Any replys would be greatly appreciated, I could use any help you can give.

I have looked at all the other post but they are all for newer trucks, I was wondering what I can do because the wire colors in some areas, if not all are different colors. Thanks again

 

JB

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