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Old 07-14-2009, 12:31 PM   #1
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Default Wacky headlight issue

Back in May I did a wiring project. I pulled all of the airbag wiring out of the harness. It was a lot of work. After I was finished, the car fired up just fine, but the headlights are weird.

I have the moss low pros. When the low beams are on, all 4 lights are on. The drivers side low beam is normal and the high beam is very dim. The passengers side low beam is dim and the high beam is very dim.

When the high beams are on, the drivers side high beam is normal, the low beam is off. On the passenger side, the high beam is dim and the low beam is very dim.

Any ideas what it might be and where I should start?
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Old 07-14-2009, 12:52 PM   #2
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When you pulled the wiring you may have messed with the relays for the headlights on the drivers side fender. The wiring for the airbags runs through the same loom at that those run though right there.

Could also be that set of grounds under the brake booster if you messed with that at all. I have had a decent amount of hassle from those.
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Old 07-14-2009, 12:57 PM   #3
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that's possible, because I tucked and ziptied the wires in that area. Would removing the horn wiring cause a problem? I don't know if it's tied in. My aftermarket horns were in bad shape.
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Old 07-14-2009, 01:02 PM   #4
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Well this is weird. I have the Mid Tenn low pro headlights (had them for 4 years or more....), and they have been working great (had to replaced bulbs but whatever). I noticed last night when I came home that my passenger side driving light is bright, and all the other 3 are dim and on... figured I'd play around with it today...
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Old 07-14-2009, 02:01 PM   #5
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Quote:
Originally Posted by johnwag View Post
that's possible, because I tucked and ziptied the wires in that area. Would removing the horn wiring cause a problem? I don't know if it's tied in. My aftermarket horns were in bad shape.
I wouldn't think that removing the horn wiring would do anything by itself but that relay is also next to hte headlight relays.

Did you cut and crimp any wires or just simply remove the airbag wires without cutting anything? If you did cut some you may have crossed the signal wire to relay and the birghts get a signal at the same time as the lows. I don't know if the lights are hooked up in series, but based on what you have decribed with one being birghter than the other, I would assume this may be the problem.

It could also be your relay for the high beams is bad. I have a set of relays form the car i am taking apart i won't be using for a while. I could send them to you to try it out and see if thats the problem.
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Old 07-19-2009, 04:33 PM   #6
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Quote:
Originally Posted by rharris19 View Post
I wouldn't think that removing the horn wiring would do anything by itself but that relay is also next to hte headlight relays.

Did you cut and crimp any wires or just simply remove the airbag wires without cutting anything? If you did cut some you may have crossed the signal wire to relay and the birghts get a signal at the same time as the lows. I don't know if the lights are hooked up in series, but based on what you have decribed with one being birghter than the other, I would assume this may be the problem.

It could also be your relay for the high beams is bad. I have a set of relays form the car i am taking apart i won't be using for a while. I could send them to you to try it out and see if thats the problem.
The only wire I cut was the horn wire. I hope I didn't cut a ground. I'll check the relays and the wiring and get back to you. If I don't have the relays at the shop, i'll PM you.

Battery is dead on the car from not driving/starting it in a while. I'm planning on looking at it today.
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Old 07-22-2009, 06:34 AM   #7
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This sounds like a ground. I had the same issue, but in reverse. My driver's side was dim. After much searching for the bad ground I gave up and just spliced a new one in, ran it to the chassis. Problem solved.
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Old 07-23-2009, 01:04 PM   #8
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I ran a new ground by running a wire from the headlight terminal here:

to a spare bolt here:


I hate dealing with little electrical gremlins like this so I always crimp+solder & heat shrink or wrap with electrical tape for maximum reliability. I also use a high conductivity paste on the grounds.
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Old 07-23-2009, 09:33 PM   #9
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Oh, so you grounded it out of that connector?

Did you do it to both sides?
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Old 07-24-2009, 12:21 AM   #10
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No, I just did it on one side. Solved my problem.
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Old 08-03-2009, 08:30 PM   #11
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Finally took the time to do it. Gary soldered the wire to the headlight ground and i did the rest. Worked like a charm. Thanks for the pics and help, guys.
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Old 05-19-2010, 07:33 PM   #12
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Default Dim Headlight problem

[QUOTE=bryanlow;433819]I ran a new ground by running a wire from the headlight terminal here:

to a spare bolt here:


Hate to bring up an old thread, but I am having the same dim headlight problem with my '90 and would like to try and run a new ground wire.
The pictures you posted are no longer available, so I was wondering if
you could post them again...I'm not sure where to attach the ground wire.
---Thanks!
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