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Old 08-25-2014, 06:37 PM   #31
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Re: Headlight problems

Headlamp circuitry is quite complex on these vehicles. Several things can control the bulbs: headlamp switch, flash to pass, autolamp, dimmer switch, and daytime running lights, and they are ultimately controlled by the BCM. The headlamps are independently fused, and use an isolated ground circuit that runs through the multifunction switch. Schematics change from year to year, and it makes a difference whether it's ZR2 or not, on the same model year vehicle!

Provided yours is NOT a ZR2, and you're having the exact same problem, with the same exact year of vehicle, Rick can explain how he got to the buss bar to fix it. It involves partially removing the underhood fuse panel. It may or may not be the problem with yours. Let us know if you need help, but be prepared for a lengthy diagnostic procedure. You'll need a basic knowledge of DC circuits, a good quality DVOM, know how to use and understand it, and lots of patience
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Old 09-25-2014, 12:39 PM   #32
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Re: Headlight problems

I'm having a similar problem with my 2000 sle. However, it's only the right low and high beam that won't come on. The yellow light (parking or caution?) works fine. I changed the bulb and it still doesn't work. I switched the fuse for the left headlight with the right and it's not the fuse. I have a feeling it's a wire that has come loose. Could you supply me with those directions to check for a loose connection? Thanks
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Old 07-27-2015, 10:46 PM   #33
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Re: Headlight problems

old_master and Rick Norwood, I am having the same exact issues with the headlights on my 1999 gmc jimmy. Can i get the information on the yellow wire. Is it the yellow with black stripe? It really pisses other drivers off when you hace to use the brights all the time. I really need to get them fixed asap. thanks for any help you can provide.
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Old 11-29-2015, 10:20 PM   #34
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Angry Re: Headlight problems

Hello to all:

I am having similar headlight issues. Instead of starting a new thread I thought I'd try adding to this one:

I have an electrical issue with my 2001 GMC Sonoma truck, 2WD 4 cyl 2.2L. My headlights refuse to turn on, both low-beam and high beam. I have checked all the fuses and none are blown. I've found the headlight power relay in the fuse box, and here's the weird thing: If I have the headlight switch turned off, I can feel that relay click when I flash the high-beam switch (but the lights still do not come on, and the dashboard indicator for high beams won't light-up either). If I turn the headlight switch to the "on" position, the aforementioned relay does nothing when trying to once again to flash the high beams. WTF....Also, where exactly is the ground connection for the headlights?

I REALLY hope it's not an issue with the darn turn-signal switch I just replaced that effing thing last year and it was an absolute NIGHTMARE doing so. Thanks in advance for any help!
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Old 03-03-2018, 07:25 AM   #35
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Re: Headlight problems

Hi old master I am having the same problem Rick was having he is not alone every problem he was having with his headlights is describing my problem the relay being hot and all my truck is a 1999 ZR2 Sonoma if you could help me find what ground wire i need to search for under the fuse block I have been suffering this carnage for the last two years throwing parts at it and spent countless hours online researching what a blessing to run across Ricks problem and this forum any help would be great thanks
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Old 03-03-2018, 07:52 AM   #36
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Re: Headlight problems

Ken, it is much easier for us to help you, if you tell us EXACTLY what your problem is, rather than jump on an old post saying it's similar to another problem......

Are you having a problem with your Auto headlights? Do they work manually? Problem with hi's or lo's, or both?

Have you tried swapping a relay? What is the name of this relay that is hot? There are 3 relays involved in this setup.....
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Old 03-03-2018, 08:20 AM   #37
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Re: Headlight problems

Good morning its the DRL Relay thats screaming hot the DRL low beam quits working it wont even come on with the headlight switch High beam works fine if you tap on the relay the low beam come back on I replaced the relay a month ago hope this helps
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Old 03-03-2018, 08:22 AM   #38
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Re: Headlight problems

Don't mean to beat a old horse but what Rick was explaining is exactly whats going on with my headlights
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Old 03-10-2018, 08:38 AM   #39
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Re: Headlight problems

I have replaced the complete UEC on two S10/Blazer vehicles due to rogue problems like this. Finding one in good condition in a wrecking yard is key to resolving the problem. Around here the spray from wet springs, humid summers, and winter road "seasoning" takes its toll. A little corrosion in the bussing and sockets within the UEC goes a long way toward creating these problems.

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Old 03-10-2018, 10:44 AM   #40
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Re: Headlight problems

Quote:
Originally Posted by Blue Bowtie View Post
I have replaced the complete UEC on two S10/Blazer vehicles due to rogue problems like this. Finding one in good condition in a wrecking yard is key to resolving the problem. Around here the spray from wet springs, humid summers, and winter road "seasoning" takes its toll. A little corrosion in the bussing and sockets within the UEC goes a long way toward creating these problems.

Thank you for the information that's where i'll start the search, the highway districts in Idaho use deicer during the winter months it's a corrosive the streets are covered with it. I'm on my way out to unbolt it and look underneath I'll let you know
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