Hey all....I was doing some work to my ride today. I got a lot done if I do say so myself. I installed my new vinyl top, new rockers and valences were installed, wheels polished...then I noticed one of my license plate lights was out.

I replaced the dark light to the leads on the working light. Bulb was good as it did light up! Hmmm must be a broken wire. Hooked up the lights again and began moving the wiring around and found the break. I trimmed the wires back and soldered and shrunk wrapped everything. Hooked it all back up and everything was working.

I worked until the sun started setting then I decide to take her for a spin around the block. I warm her up, check all the lights. All's good so I back out of the drive way and get about 20 yards and smoke starts pouring out from underneath the dash!!!!
I shut her down and see a glowing wire under the fuse block. Well I gotta get her back in the driveway so I start her back up and park her quickly. I couldn't see the where the wire was going so I drop the fuse block. It seems to be a red wire that goes from the block (3rd from right0 to the headlight switch and a white wire with red stripes on the switch that are completely wasted. Those wires and a few that were in contact with them. Now only the headlights work. They turn on and will only go up but will not go back down. All other lighting is not working.

My questions are

1) Would hooking up the license plate lights back up incorrectly have caused this?
2) Why didn't the fuse blow before the wiring melted?
3) Do I need to replace my headlight switch when I get the wiring replaced?
4) Why does this car love taking 1 step forward and 2 steps back!!! LOL

Thanks in advance

As far as I can tell, there are no fuses in series with the 2 wires that fried in your car.

How long after you turned the lights on did you see the smoke?

There are 2 red wires on the light switch. The one on pin 30 goes straight to the battery. The red wire on pin 15 goes to the ignition switch and is switched on/off.

There are 2 red/white wires on the light switch. The one on Pin 15 goes to the fresh air blower and the one on Pin 56 goes to the high beam switch and powers the head lights.

To answer your questions:

1) Would hooking up the license plate lights back up incorrectly have caused this?

Hooking up the license plate lights shouldn't cause the melting. They are powered by Fuse 7.

2) Why didn't the fuse blow before the wiring melted?

Because there are no fuses in line with these wires. Welcome to 1970's auto tech.

3) Do I need to replace my headlight switch when I get the wiring replaced?

Chances are no. All the headlight switch does is switch 12V. You can basically short any headlight switch pin to any other headlight switch pin and you will not cause a short.


I think you fried the wire on Pin 30 of the headlight switch. This would explain why your lights don't go down. Pin 30b powers the "go down" part of the headlights. and Pin 30b gets its power from Pin 30.

Do any other lights work now?

Here's some pics. I just got back from looking at it more. It seems two wires from the ignition switch harness (brown wires) go to the emergency flasher switch. Those wires burnt up. Also the red wire that goes from the fuse block to the headlight switch burnt up. Here are pic that I had to re-size.

Fuse block: screwdriver pointing wire from post that fried (Red)
Click to view attachment

Headlight switch wires (Red and Grey w/red stripe:
Click to view attachment

Emergency Switch wires (Brown):
Click to view attachment

(Quote:How long after you turned the lights on did you see the smoke?)

Well I let the car warm up while I was adjusting the headlamps so I would say 5 min.

(Quote Do any other lights work now?)

I didn't try the turn signals or the flashers, but with the headlight switch in the full on position, only the headlamps were on. All others were dark.

Any ideas on the cause?

Dunno... but that's ugly!

I can tell you how to use quote tags.



The result of that looks like this:

Thanks Gint! I'll figure out the ins/outs of this site when I stop my car from catching on fire! ! Thanks for the info though

If the positive licence plate wire touched ground or you had a shorted bulb, you could cause that damage. carefully go through each wire one at a time and replace with new wire. Copper conducts heat very well. Do not be suprised if you find more damage further away from the switch.

I only checked the rear trunk. All the wires there were okay. looks like a long day of wire tracing tomorrow!
What do you think of a faulty ignition switch or the starter/solenoid? Could this be the culprit?

You have some sort of short that I would guess has nothing to do with your working on the license lights. If you short those, you "should" blow fuse 7.

The fuse you have your screwdriver on is likely fuse 10 which connects through a red wire to pin 30 of the headlight switch. Pin 30 powers all the other lights on the car not including the turn signals.

I say should because it looks like there have been some changes to your wiring. Note in the pic below the aftermarket spade connector on the position to the right of your screwdriver. Plus the blue aftermarket crimp connector too.

Click to view attachment

What is this brown wire connected to? The extra wiring from someone before needs to be flushed out to make sure nothing is improperly connected. Go through all the burnt wires and see where they go.

Click to view attachment

Where does this red/white wire connect to?

Click to view attachment

Nothong worse than to see carnage like that. Crispy wires and globs of melted plastic. I have repaired several chassis harnesses and some of them have had that level of damage. I may be building new chassis harnesses in the future but for now your only optoin is to repair yours or find a donor in better condition.

If you repair, evaluate it carefully, if its more than about a dozen wires that need replacement, you will probably find it easier in the long run to remove the entire harness from the car and do the repairs. Repairs are much easier to do out of the car and you will no doubt find additional concealed damage when its out of the car. Its also easier to restore the fusebox, switches and other items if its out.

Just so you all know, IIRC, the pins on the license plate lights ARE power/ground specific. The ground pins are apt to come into contact with ground, the hot side isn't. I've seen evidence of improper connections there more than once.

The Cap'n