Need some electrical help for my 72 please.

[kentucky_smith]

Driving along and hear loud pop, I thought it was a backfire, but everything dead. Get it safely off the road and find a wire coming off the battery has burnt up. It's the red wire going into wiring harness off the battery, not the one going to the starter.

Put a jumper wire in there, radio and accessories come on, but no start. Also, red wire gets really hot. All fuses in fuse box are good and everything seems to work. Red wire going to left side fender looks great, it splits off to voltage regulator(?) or back to fuse panel. Don't see any frays or anywhere it could be shorting. Black wire that comes off the same block on the inner fender next to battery seemed to have an inline fuse that may have been burnt or I may have broken it trying to get the rubber boot off. Jumpered it too. Still no start.


Back of fuse box panel does seemed gacked up. Ideas?

The green jumper wire is a temp just now. It was all nice and sealed up. At first, I thought it was the battery sliding into it, but now not so sure.






Took the wife and sun around to our family cemetaries today, then to his baseball game. Were having an awesome Memorial Day weekend before it broke down about 2 miles from home. Towed it home with my 04 F150.

Here's good pics of the truck. Help me figure this out quick and I'll post pics of the wife.

[Norcal72]

You have a short somewhere. The connections look melted. Hooking a battery up will just make things worse. Find the short, could be easy or a nightmare. I would start looking into a total rewire. If you burned that fat of a wire, other stuff fried way before. Good luck.

[Avitech]

sounds like your fusible link burned out. That would indicate a short somewhere before the fuse box. If you aren't getting the starter to work check that wiring first. The bulkhead connector is sealed from the factory with a rubbery material so it is supposed to look gacked up. :-)

[ray_mcavoy]

I agree ... sounds like a short circuit burned out the fusible link that protects the red wire. And jumpering it will just lead to additional damage (the red wire should not get hot).

For troubleshooting purposes, I'd recommend temporarily connecting a test light in place of the burned out fusible link feeding the red wire. The resistance of the test light's bulb will limit the current flow through the short circuit to the point where it won't do additional damage to the wiring. And the light should go out once you locate & remove the short. Do this testing with the ignition switch off so there won't be any loads that would keep the test light on.

Since you said the red wire looks good, the short circuit could possibly be internal to the voltage regulator or alternator. Temporarily disconnecting them (while watching for the test light to go out) would be a quick and easy way to see if they're the source of the short.

As for that small black wire with the inline fuse, that goes to the "BATTERY" gauge. That won't keep the truck from starting/running. So concentrate on finding / repairing the short circuit and replacing the fusible link first.

[kentucky_smith]

Originally Posted by ray_mcavoy

I agree ... sounds like a short circuit burned out the fusible link that protects the red wire. And jumpering it will just lead to additional damage (the red wire should not get hot).

For troubleshooting purposes, I'd recommend temporarily connecting a test light in place of the burned out fusible link feeding the red wire. The resistance of the test light's bulb will limit the current flow through the short circuit to the point where it won't do additional damage to the wiring. And the light should go out once you locate & remove the short. Do this testing with the ignition switch off so there won't be any loads that would keep the test light on.

Since you said the red wire looks good, the short circuit could possibly be internal to the voltage regulator or alternator. Temporarily disconnecting them (while watching for the test light to go out) would be a quick and easy way to see if they're the source of the short.

As for that small black wire with the inline fuse, that goes to the "BATTERY" gauge. That won't keep the truck from starting/running. So concentrate on finding / repairing the short circuit and replacing the fusible link first.

Very helpful, thank you. I tried the voltage regulator, it's not that. I haven't gotten underneath it, but may be something with the solenoid.