Headlight Wiring Decided to burn last night..

[markpink]

Last night I decide to go on a cruise my with son with 1977 which has never had electrical problems in the three years that I have owned it.

I get to the end of the street and turn my lights on.

In seconds, there is smoke everywhere. I pull over look under the dash and see some wiring glowing orange.. I pull the wires out and the smoke stops after a while.

The headlight wires have melted. One wire's insulation is completely gone as far as I can see.

But the car starts and I drive it back up the street to the house. Everything works except the headlights, which I don't dare to try.

I take the wooden dash panel out this morning and it looks like most of the wires that connect to the headlight switch are melted and need to be replaced. The actual headline switch melted. Trying to find trace the wires looks like a real pain. They seem to disappear way in the back of the cavity behind the instrument panel.

Anyone have an issue like this.. What did it take to repair it?

Do I trace and repair the wires or Do I just run new wires and maybe a relay for the head lights.


I just got my car's yearly inspection sticker yesterday morning, so the last time the headlights were used were doing the inspection, I guess I am lucky that the car didn't burst on fire when the mechanic turned the headlights on during the inspection.



thanks


Mark

[manoa matt]

The headlight relay is ment to take the electrical load off the ignition switch, but may be helpful in your situation. Unfortunatly you'll need to trace all the burnt wires to their sources to confirm there is not a short somewhere. I have a wiring harness from a 76 that I can supply you with most if not all of the wires needed. matt.scarton@gmail.com

[Fiat88]

Wow man that must of been really scary! I remember when I burned my wiper motor out a few months ago and smelled smoke in the cabin, smoke came out of the steering column. Get really nervous anytime something like that happens. It's a good idea to keep a small fire extinguisher in the back seat just in case. That's what i do.

[pooldoctorstl]

The headlight circuit on our cars does not use a relay so the entire load runs through the switch. It is a good idea to install 2 relays, one for the low beams and one for the high. That way the load for the lights doesn't go through the switch. To learn how to do it, do a search here in the forum for "headlight relay" and you will find numerous posts on the subject. Get a wiring diagram and you can rewire it, or pick up a harness like Matt said and replace the burned wires. But whatever you do, install the relays. They are $5.99 ea in the lighting isle at AutoZone or most parts stores. You should also replace the swtch.

Jeff

[katsi]

I agree, you need to go ahead and install relays. The wiring for the headlights themselves is not that difficult. Just buy some brown wire and start replacing. Make sure to check inside the white couplings for shorts as well. Mine actually shorted out inside the plastic harness. Look at the bright side, you can install a cool lighted toggle for your lights now. OHHH, I think I may just do that anyway. That toggle is a bitch to work with though unless you got some really flexible wrists and fingers. Can be done though. Good luck. Hay, it could have been A LOT WORSE.

[markpink]

Yeah it could have been a total loss.

And the rest of the car seems to be still working fine except for the light circuit.

I got relays and wire and wiring diagrams, but it looks like I may have to take the dashboard completely off to trace the wires.

The wires seem to disappear in back of the instrument panel cavity and I get seem to find out where they go with the limited view if the instrument panel being removed.

And it's really too hot outside to work on the damn thing and the garage is even hotter. I need to work on this at night.


thanks

mark

[katsi]

No need to removethe dash. You can see the wires by just removing the instriment cluster. You can pretty much abandon the burnt wires and just cut them out and start from scratch. I had to do this and, it's really not that difficult. TEDIOUS -YES but not that difficult. You should try to soder whenever possible as it makes a better connection. Remember, you can circomvent the big plugs now but, I went ahead and put in connectors at the plug sections anyway. The brown wire starts from the ignition and travels up to the turn signals. It then goes to the light switch and then out (going by memmory so you will definatly need a wiring diagram). Really, just cut the old wires out and start from scratch using the wiring diagram. Their are lots of holes to go through the firewall. You can tape to the original wiring harness. Plus, once you wire in the relays, the wires going to the right front headlight are useless and get abandoned.

[brad131a4]

Sounds to me like the switch itself shorted out. If you are going to run relays then I'd follow the post above and just abandon the stock wiring hareness. Don't remove it just incase you need to find out how the wires are routed in the future.
The only place I would cut the original harness is by the headlights to attach them to the relays.
The only other thing is to find out on the colum harness which is the low and high beam to be able to power up the relay's.
I think someone here on this site has a wiring diagram on how to do this.
I you need any help I also have a 77 and I have the dash out right now I could look at it and see what wires go were and how you could wire it up.

[markpink]

Hey Everyone.

The repair went faster that I thought. THe wiring is done. The relays are in and I just came back from a 1 hour ride in the dark (with the lights on) through the back roads of New Hampshire without a problem. The headlights do seem brighter now.

Thanks for everyone's help.


Mark

[mandragora48]

Sounds like the first thing you need is an accurate wiring diagram. I got mine from International Auto Parts in VA, and the version they print is relatively easy to follow. The main reason you need this is to determine how much your car's wiring has already been altered. From the sudden onset and dramatic smoke, it sounds as if you either have a direct short (cause by a loose wire or chafed or melted insulation) or a missing/disconnected ground wire. The former SHOULD have blown a fuse, rather than fried the wiring; that's why you need to compare what you have to the stock system. Regarding the latter, if the car is missing one of its major ground paths, those are NOT fused, and the high-current headlight circuit will try to send the current through any other available path to ground. If you can still see the original color of fried wire(s) Fiat ground wires are almost always black (nero). On our 1978, the (+) headlight wires exiting the fuse block are green (right) and green/black (left) for the low beams and gray and gray/black for the highs. With everything in the car turned OFF, you can use the ohmeter function of a VOM to check whether any of those wires is shorting to a ground.

Once you have working headlights, yes, you should install a relay system. Stock wiring runs all the current for the lights through a small contact point in the steering column switch. When that gets hot (maybe due to installation of modern, higher wattage headlights) the plastic structure of the switch melts, further worsening the electrical contact, which causes it to get even hotter, etc. Mounting a relay in the front part of the engine bay (above the windshield washer bag, perhaps, which is where I did it) allows the stock headlight circuit to carry only the current needed to activate the relay. You'll need to run a hefty (#10) wire from the positive alternator output to the relay's input side (typically terminal #30). Use the existing wire to the headlight as the positive lead to the relay coil (terminal #85) and a short (black) wire between terminal #86 and a chassis ground. Then run the OUTPUT (terminal #87) of the relay TO A FUSE SYSTEM with the headlights connected to the output side of the fuses. I've had good luck getting fuse blocks for glass in-line fuses at Radio Shack. If you attach a 4" x 4" square of plywood or masonite to the engine bay, you can affix the fuses and relays all to it. (You'll want to run two relays--one for high beams, one for lows. Bosch relay # 0-332-019-150 is a good choice for this, as it has an integral moutning tab for attaching the relay to the wood block. Good luck.