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Electrical problems (yay...)

I Can't get my headlights to work. I have a 1968 mustang, and I'm pretty sure all the wiring is original. I replaced the headlight switch because that also controlled the dash lighting level, which would flicker as I juggled the switch. The headlights still don't work (and didn't before the new switch). After lots of testing, I have found that at the headlight bulb, there is a voltage reading on the negative lead. (the headlight plug has three leads, hi lo and ground, and either lo and ground or hi and ground both have voltage readings at the same time depending on where the beam selector is set) Because of this, I think there are some crossed wires somewhere in the loom. Does this sound reasonable to you or have I over looked something? Is it hard to rewire parts of electrical systems? Also- there are a few other electrical problems with the car, and the wring is all very old, is it worth my time to buy one of those painless wiring kits to rewire the entire car and can I even do it? Can I be cheap and buy a universal ford wiring kit or do I need to spend more money and get a vehicle-specific 1968 ford mustang wiring kit? thanks for the info everyone!

Reply to
bobar3425
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That's good. Are you using a digital meter or are you using an analogue meter? Try again with a test bulb and see what happens when you measure between the high beam pin or the low beam pin and a real ground, like the block.

Maybe, but if you are using a DVM and there is any tiny leakage voltage you will see it. This will cause all kinds of indications like the one you describe.

Maybe your ground is open. Maybe your headlight relay is bad. What do you see on the headlight relay with the test lamp?

Old wiring can be okay, or it can be a total disaster. I have never used any of the kids, and have only made the body harnesses up by hand. It's no fun.

Find the problems one at a time... if one of the problems turns out to be deteriorating cable, then it's time to replace harnesses and looms.

--scott

Reply to
Scott Dorsey

I would be checking the dimmer switch out. If it's that floor one, they die all the time. The aftermarket ones are crap so if you need I would try to get OEM.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: N> I Can't get my headlights to work. I have a 1968 mustang, and I'm
Reply to
Mike Romain

thanks guys. I already tested the floor dimmer and it was fine. The headlight relay is fine too. I'm pretty sure I've narrowed it down to the segment of circuitry between the dimmer and the lamps.

Reply to
bobar3425

Does that include the lamp grounds? Does that include the connectors? The connectors are far more apt to fail than the wiring. If both high and low beam is gone, the ground is the only thing common to both once you get past the switch.

--scott

Reply to
Scott Dorsey

I would take it that you have full voltage going into and coming out of one of the wires on the floor dimmer then? I backfeed the plug with my meter to check this.

The reason I ask is because when the headlight switch dies, it normally takes out the spade connector in the plug on the harness side too.

It would also be very unusual for both the high and low beam wires to be broken between the dimmer and the lights.

Does the body have a ground strap or cable that is broken? I test that using a booster cable between the battery negative and the body or even the black wire on the headlight.

Your 68 has a headlight relay? They can be sneaky for having a corroded pin or it's socket on them. Does it click when the switch is thrown? Is there then power coming out of it?

What about the fuse link for the headlight harness? Their should be some 8" or so fat soft rubber coated wires with one loop end and a fat tube crimp on the other end bolted to the solenoid on the fender where the battery cable connects to it. This is a safety link in case of a short.

If blown, it should flop loose and it might show a black mark on it. It will not show continuity with a meter or show voltage past the tube crimp when blown. The headlight fuse link wire is a 14 ga. one protecting the 10 ga. harness.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Reply to
Mike Romain

If you have power at the ground side of the circuit, then the lamp(lamp) is not getting a ground, so you have to have an open somewhere at the ground circuit. try and ground one of the ground terminals of the lamp. Find out which of the two lamps provides the constant ground, if you do this then both headlights will come on.

Reply to
ixbeavisxi

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