1992 Ford Bronco headlight (blk) wire over heating and melt

Tiny
SKIPBOND
  • MEMBER
  • 1992 FORD BRONCO
  • V8
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
My drivers side headlight will not work on low beam, but works on high beam. However the black wire which is middle prong position on bulb is heating to the point where it is melting the surrounding connector housing. What's the problem. Where is the solution located and how do I change it. I am thinking faulty relay. Need solution as fast as possible my job is at night time.
Saturday, March 7th, 2009 AT 4:39 AM

7 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Black is the ground wire, create a new ground wire and attach it it clean bright metal with a sheet metal screw. Too much resistance in the old wire/circuit.
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Saturday, March 7th, 2009 AT 6:53 AM
Tiny
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Thanks merlin for the quick reply. Based on what you are saying would directly running the ground from the plug to ground be the same thing? I did that and low beams still dont work and the ground is heating up still.
MY CAR IS MY JOB IS MY LIFE LOL
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Saturday, March 7th, 2009 AT 8:55 PM
Tiny
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Have you replaced the bulb? Use a plain old incandesant test light - they not only will show potential (voltage), but will also load the circuit you're testing slightly ( a DVOM won't). Check pwer for high & low beam with test light grounded at batt, if N/G Fords have a lot of "connector" problems - there may be one that you can clean up or bypass - a "wiring diagram" manual & a Workshop Manual from Ford can be handy - there's a bunch on ebay right now from all the failed dealerships.
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Saturday, March 7th, 2009 AT 9:21 PM
Tiny
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(help). Light bulb connector and bulb itself have been changed. And since there are only three different wires I know I connected new plug right. Old one melted and contacts dont touch. My first problem was no low beam but high beam only. Then it went from that, after three weeks or so, to currently blk wire over heating and melting connector. The high beam did work fine for over 3 weeks.
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Saturday, March 7th, 2009 AT 10:08 PM
Tiny
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You really should get low beams going first. But for "High" maybe the wire you added is too small or not correct type?
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Saturday, March 7th, 2009 AT 10:28 PM
Tiny
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Merlin, I assume you will revisit this so another question to further solution. If my (pass) side light is working fine and the connecting wires are all same color codes, which they are, could I merely splice into those wires at the headlight connector and run to other nonworking headlight with out losing strength of headlights and would they work just as well? Do they share different fuses or power supplies? Could the problem in the bad light be somewhere in the lines?
Oh, I ran the ground straight from the connectors wire to a good ground.I think it was at least. It still overheated after in about a minute.
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Sunday, March 8th, 2009 AT 4:05 AM
Tiny
MERLIN2021
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Un tape the harness on the bad side, it souds to me like one of the power wires may be touching the ground or there is some greenish corrosion and a section of wire may need to be replaced. The wires melt because of too much resistance, this can happen in older vehicles when the wire inside the insulation is discolored(corosion).
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Sunday, March 8th, 2009 AT 8:17 AM

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