Headlights Will Not Shut Off

tattoome · November 25, 2006

I have a 98 Chevrolet Z71 and today installed a new cd player. I went ahead and got the easy plug and play wiring harness and all, cd player works great. The major problem though is that my headlights will no longer shut off. Even with the switch in the off position they stay on, and when you do turn the switch to the on position it just turns on the parking lamps as it normally would, but the switch will not shut off the headlights. At first i thought that it was something to do with the new cd player, so i unhooked it, and with absolutely nothing plugged up as far as a radio is concerned, tried them again. Still they will not shut off. I was thinking that it could be the DRL relay, so i pulled it and the fuse that is located in the fuse block inside the cab of my truck, and they still will not shut off. At this point, the only way to shut them off is to unhook the negative battery lead. I was thinking that the headlight switch itself could be to blame, but im not sure either way. HELP

tattoome · November 26, 2006

What are the odds that your installation of that wiring harness was not the cause of your new problem? Slim to none I'd say. Did you completely remove the added on harness from the vehicle? If not, do so.

There's a circuit in the radio harness that goes right to the headlight dimmer switch. This is so that when you turn on your headlights, the radio gets that signal and dims the display to night time mode.

So remove that harness and plug the radio back into the factory harness. If putting EVERYTHING back to the way it was doesn't fix it, perhaps something caused damage to the DRL module (not the relay), which controls the headlights too. Doesn't seem possible, but I don't know the configuration of whatever it was you plugged in.

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I tried putting the factory radio back in and it doesnt make any difference, they still burn. The harness that I purchased with the new radio is actually a factory specific harness, the box even has my year model truck listed on it. Its made by Metra and it just plugs into the original harness and then into the back of the new cd player. I have no clue what to try. I have already removed the fuse for the DRLs and the voltage drop diode. I have a wiring diagram for everything on my truck and I found the DRL module earlier this morning. I removed the wires that actually supply the DRL relay from the module, because i figured if it was a DRL problem, if it didnt exist that would solve my problem, but it didnt. The only thing i know is that when i plugged in the radio my headlights didnt turn off. No matter what radio is in the dash, they still burn. My neighbor has the same truck as mine so i used his headlight switch and it didnt make a difference either. The wierd thing is I have had the DRL fuse removed from my truck for around 3 years now, so for the last 3 years the DRLs havent been burning anyway, so if it was the DRL system i cant understand why they would all of a sudden not shut off without the fuse being in. I have noticed that my headlights are operating at normal wattage, there is no drop in brightness at all, which is there again strange because i was under the impression that the DRLs did not operate your headlights at full capacity.

GM-Tech · November 26, 2006

i was under the impression that the DRLs did not operate your headlights at full capacity.

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That is correct. You don't have the separate DRL's like the new body style trucks.

Can you switch between high and low beams?

tattoome · November 26, 2006

i was under the impression that the DRLs did not operate your headlights at full capacity.

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That is correct. You don't have the separate DRL's like the new body style trucks.

Can you switch between high and low beams?

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Yes, my highbeam lights work fine. I know this is a pain trying to picture without seeing my truck, but if you can imagine the headlight switch on my dash being in the off position, everything should naturally be off. Well, my headlights are still burning, i can turn them to the on position and they still burn and they also engage my parking lights and taillights like it normally should, and i can click my highbeams on and they work fine as well. But, i can turn the switch back to the off position and everything shuts off as normal except the headlights, they still burn. I actually have them unplugged from the bulbs themselves right now to keep from unhooking the negative battery cable. I've talked to a few people here locally and cant come up with any good reason why this is taking place. This is why i initially thought it was a problem with the headlight switch but ive already tried replacing it and it doesnt seem to work. I have small ad ons on my truck like driving lights and i got some led bulbs here and there but ive had all of these items for well over 2 years now so i figured i could rule of that being a problem. Everything happened when i changed the cd player, and believe it or not the cd player now works fine, just not my lights. Oh, I changed the cd player because my factory one had just quit reading discs. I actually stopped by the local chevrolet dealer one day and they suggested that i manually remove the cd player and clean the lense myself, cause cd cleaners were not working. I did this and naturally it didnt work, so this is why i chose to just buy an aftermarket cd player. If i had have known i would be faced with this kind of issue i would have just left the original one in.

GM-Tech · November 26, 2006

i can click my highbeams on and they work fine as well.

You missed the point of my question. When you switch the dimmer from low to high, do the low beams go off like they should or do they stay on even with the high beams on?

Haven't looked at a '98 lately, but it seems to me they had two types of headlight setups. Quad, which is individual sealed beams or the single assembly with replaceable bulbs.

Do you have the quad headlights or do you have the non-sealed beam type?

tattoome · November 26, 2006

i can click my highbeams on and they work fine as well.

You missed the point of my question. When you switch the dimmer from low to high, do the low beams go off like they should or do they stay on even with the high beams on?

Haven't looked at a '98 lately, but it seems to me they had two types of headlight setups. Quad, which is individual sealed beams or the single assembly with replaceable bulbs.

Do you have the quad headlights or do you have the non-sealed beam type?

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No, they dont go off when i switch the high beams on, and even if there werent a problem already they wouldnt go off, i added a relay about a year ago that allows my low beams to stay on when my high beams are engaged. My headlights are the quad type, when looking at the front of my truck there are actually 4 halogen bulbs 2 pair (9006) which are my low beams and 2 pair (9005) which are my high beams.

tattoome · November 26, 2006

i can click my highbeams on and they work fine as well.

You missed the point of my question. When you switch the dimmer from low to high, do the low beams go off like they should or do they stay on even with the high beams on?

Haven't looked at a '98 lately, but it seems to me they had two types of headlight setups. Quad, which is individual sealed beams or the single assembly with replaceable bulbs.

Do you have the quad headlights or do you have the non-sealed beam type?

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No, they dont go off when i switch the high beams on, and even if there werent a problem already they wouldnt go off, i added a relay about a year ago that allows my low beams to stay on when my high beams are engaged. My headlights are the quad type, when looking at the front of my truck there are actually 4 halogen bulbs 2 pair (9006) which are my low beams and 2 pair (9005) which are my high beams.

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Now that i think about it the way you are describing them mine are the single assembly i guess. Basically, when you look at my truck I have a low and high beam bulb for each side. Hope this helps.

GM-Tech · November 26, 2006

even if there werent a problem already they wouldnt go off, i added a relay about a year ago that allows my low beams to stay on when my high beams are engaged.

That's information that's should have been stated in the beginning.

Okay, I'm basically done here. I'm not going to scratch my head and pour over schematics on a problem with a system that's been modifed from original design.

tattoome · November 26, 2006

even if there werent a problem already they wouldnt go off, i added a relay about a year ago that allows my low beams to stay on when my high beams are engaged.

That's information that's should have been stated in the beginning.

Okay, I'm basically done here. I'm not going to scratch my head and pour over schematics on a problem with a system that's been modifed from original design.

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To be quite honest with you I just didnt think about it when I first posted on my problem. I appreciate everything that you have suggested so far, but to let you know the relay that I am speaking of is currently unplugged from my truck. It was simple to wire up, but when i did i installed it with male and female connectors so if there ever was a problem the relay could be terminated quickly. So my problem still exists. If you dont have any intentions on helping me anymore i understand your frustration because believe me I am highly frustrated as well, but honestly this was just a simple mistake on my part of not telling you this, i just didnt think about it. The only thing currently on my truck that is aftermarket is the cd player, ive taked everything else off in hopes of fixing my problems, and i have taken this cd player out thinking that is what caused this mess, but no luck yet. Somewhere along the lines i think the addition of the cd player has indeed caused the problem, i just dont know why or how.

GM-Tech · November 26, 2006

One last little tip. Power for the low beams comes from the DRL relay. If you unplug that, which I think you said you already did, the lights should go out. The lights get power from nowhere else that I can see in the schematics. Otherwise, a wiring problem or modification is backfeeding power into that circuit.

If pulling the relay does't do turn the lights off, you're just going to have to track down where they're getting their power. Not much else I can tell you, really.

tattoome · November 26, 2006

One last little tip. Power for the low beams comes from the DRL relay. If you unplug that, which I think you said you already did, the lights should go out. The lights get power from nowhere else that I can see in the schematics. Otherwise, a wiring problem or modification is backfeeding power into that circuit.

If pulling the relay does't do turn the lights off, you're just going to have to track down where they're getting their power. Not much else I can tell you, really.

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Thanks, in the wiring diagram that I have (Haynes Manual) I tracked down the DRL module and killed what looks to be the power to the relay itself, which i figured would stop power supply to the relay , but ive had quite a hard time finding the actual relay. Im thinking that it is located somewhere under the dash near the passenger side of my truck, with it being nightime here where im at ill probably tackle finding this tomorrow evening, but if you have any ideas of the exact location of the relay if you will just post them here, itll be of a great help. Thanks.

GM-Tech · November 26, 2006

There's a "convenience" center (which is never convenient!) on the firewall, just above where your left foot would rest while driving. It has a black plastic cover over it. The relay is supposed to be in there.

tattoome · November 27, 2006

There's a "convenience" center (which is never convenient!) on the firewall, just above where your left foot would rest while driving. It has a black plastic cover over it. The relay is supposed to be in there.

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Thank you sir, i will definately check this out tomorrow when i get home from work, my brain is completely tired of thinking about it for one day. Ill post and let you know what happens.

GM-Tech · November 26, 2006

What are the odds that your installation of that wiring harness was not the cause of your new problem? Slim to none I'd say. Did you completely remove the added on harness from the vehicle? If not, do so.

There's a circuit in the radio harness that goes right to the headlight dimmer switch. This is so that when you turn on your headlights, the radio gets that signal and dims the display to night time mode.

So remove that harness and plug the radio back into the factory harness. If putting EVERYTHING back to the way it was doesn't fix it, perhaps something caused damage to the DRL module (not the relay), which controls the headlights too. Doesn't seem possible, but I don't know the configuration of whatever it was you plugged in.