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Headlights wont turn off

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126K views 29 replies 24 participants last post by  Ravalli Surfer 
#1 ·
My 2003 TB battery died - must have had something left on, only clicks on attempting to start, but the weird thing is that the headlights turned on by themselves with the switch off, and will not turn on or off. Anyone see this before? If so, what is the fix? I have my duramax van hooked to it now for jump starting, as the batt is low enough that the charger won't even send it a charge.

Thanks for the help
 
#10 ·
Automatic Headlights turn on while vehicle is off....

Have a different problem I have never run in to before.... My headlights randomly come on while the Trailblazer is parked! Here is the background so far:

Came out of work last night to find a dead battery. Jumped it, and put it on the charger when I got home. The headlights were off.

Went out with my wife in her car, leaving the charger on automatic for an hour. When we got home, the lights on the TB were ON. Flicked a couple of the switches and they went off. Let the battery recharge again without the light coming on, and disconnected the battery for the night.

Drove the TB to work this morning, and parked it facing my office window where I could see it. Lights went off after the standard delay when the car was shut off. 45 minutes later, I noticed the lights were ON! Flicked the high beam switch on the steering column once to engage them, and the low beams shut off.

Other notes: Its been cloudy & rainy the past 2 days in that area, so the general light level is lower. Also, I just passed 200,000 miles a week ago, but I didn't celebrate so maybe it is just being cranky.....

Any insight as to were to look at the fuse/electrical system would be greatly appreciated!
 
#13 ·
Ok! lol.. at first the headlights wouldnt turn off they stayed on until it ran my battery dead. so i took it to Advance Auto. and they tested the Battery and alternater and they said it had a bad battery cell. so i bought a new one and put it in... 2 days later same thing except now they go off but come back on and stay on. i got home friday night at 10:30 the lights went out when i went outside at 11:30 they was on.. come back home at 12 and they went out. woke up the next morning to a dead battery. took it to a auto shop. and after more than 24 hours he called me and said he thinks its the after market alarm system. so he took it out. charged me 90 for labor and 10 for supplys.. so i paid $107.25.. brought it home and surpise surpise the headlights wont go off again..
 
#14 ·
After I figured out it was the headlight relay, I have never had the problem again. In fact, I was at Advanced Auto one day when someone came in with the exact same problem. The staff didn't believe me until I took them out with the customer and flipped the two relays around... She got out of there with only a simple relay and nothing in labor!

I would be tempted to take the car back and have the guy re-install the alarm system, plus give you your money back.

BTW, I like the floodwall murals!
 
#15 ·
burned fingers

Wife just came home and had the same problem with the low beam lights staying on. I read these threads and decided to check the relays. When I touched relay #46 to pull out with my fingers I found out very quickly that this was the problem. The relay was very HOT!

Thanks for the post, saved me a lot of time and probably $$$ if I had taken it to a shop.

But for the next person with the same problem, don't grab the relay with bare fingers.
 
#20 ·
Same problem with the lights going on and off. My car is possessed! I think I have read through this entire thread - does replacing the relays work in all cases or is there something else I should consider. Thank you!
Its the cheap try first before you get into expensive electrical troubleshooting .
 
#23 ·
2004 Trailblazer thanks for fixing problem

Hi All
Came home from work last week and the headlights would turn off. The Lights ran the battery down. check the forum and saw several of the same problem with the relay fuse #46. Bought it at Advance Auto $39.95. Put it in and jump started the car. Lights work great.
Thanks everyone. This blog is a great great help to me. Also thanks to the person for posting the actual part number of the relay fuse.
 
#25 ·
I'm having the exact same problem.. only that i *already replaced* that very same relay last year - it decided to stop working one day.

Interestingly enough, I see there's a small shutoff time when the headlights turn off. Once they're off, they turn back on about a half second later.

fwiw, the new relay says 'BWD' on it, I believe I got it from O'Reilly.

Is there a chance I need yet another new relay, or is there something else wrong?
 
#29 ·
I'm having the same issue work my 03 TB. Except that I don't have any brake lights either, all three are out. I have replaced the switch on the pedal twice in case one was bad, the circuit boards, the bulbs, the switch connector, the fuses. I have done everything except replace the wiring or checked the grounds.
I have a Power probe but for the life of me can't figure out how to use it to power the system once I have disconnected or from the Battery. I want to start at the brake lights and work my way to the fuse box when work each connection along that circuite until I find the problem. It didn't come with a manual and the disk assumes you know how to use it. I know AC wiring but hey confused when it comes to DC. I eventually work or out but nothing like AC. And I can't find anything online that dumbs it down and gives a clear explanation. I'm sure the headlights and brake light issues are separate, but really odd then happened within a few days off each other. I'm gonna to try the relays now.
 
#30 ·
I'm having the same issue work my 03 TB. Except that I don't have any brake lights either, all three are out. I have replaced the switch on the pedal twice in case one was bad, the circuit boards, the bulbs, the switch connector, the fuses. I have done everything except replace the wiring or checked the grounds.
I have a Power probe but for the life of me can't figure out how to use it to power the system once I have disconnected or from the Battery. I want to start at the brake lights and work my way to the fuse box when work each connection along that circuite until I find the problem. It didn't come with a manual and the disk assumes you know how to use it. I know AC wiring but hey confused when it comes to DC. I eventually work or out but nothing like AC. And I can't find anything online that dumbs it down and gives a clear explanation. I'm sure the headlights and brake light issues are separate, but really odd then happened within a few days off each other. I'm gonna to try the relays now.
It's confusing to start at the source of the power and go out to the failed spot ..... so you're kinda doing it right.

Start where the failed object is (a non-working light, f'rinstance) and follow the wire from it until you find where the electricity starts.

I'd just use a test light - the kind with a wire on one end with an alligator clip and a surgically sharp spike on the other to probe it into wires or sockets, etc. Just ground the alligator and look for elusive electricity.

If you want to use a little more sophistication, get a 'Bed Of Nails" tip for your test light - and you can also use it on a meter as a non-destructive testing probe.

54792
 
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