OPEN CIRCUIT in electrical system

[7-T-1Gold]

Hello Ford truck group!

I am trying to locate an open circuit in my '71 250's electrical system. When I touch the negative cable to the battery terminal, I see minute sparking. I disconnect leads to the starter solenoid one at a time and the only lead that sparks is a medium diameter black wire with an orange inline fuse. I unravel the harness and follow it to the back of the alternator. There, the wire housing color is orange and is also orange going into the voltage regulator. The alternator tests fine so am wondering if the regulator is defective or the wiring.

Thanks!
Alex

[390FE1972]

Did you find out anything on your issue?

[68fe360]

I have delt with this sort of thing on many cars/trucks. Normaly there can be a small crackle or spark. This is nothing to worry about. It happens because items like the radio often have 12 volt memory saving connections that are hot all the time.

On the other hand if it's a rather large and strong spark you likely have an issue someware. Here's a way to help narrow down ware to focus on.

It's a PITA process of pulling a fuse and checking if it still happens. Goes down to just the normal crackle and minor spark... well now you at least know which circuit the problem is on, and you can get down to the business of checking connections, devices, and wires.

The best way to determine if yes you have a problem in your wiring is to check for a voltage draw with everything shutdown. It's been a while since I had to do this type of test, and I don't want to give you the wrong description of how to do it. It can be done with a simple volt meter. I will refresh my aging memory, and make a 2nd post with the instructions. It's totaly possibly you don't have an issue, and it's just the normal spark. Learning how to do this test though will serve you well owning an old truck, and the electrical problems they often have.

[7-T-1Gold]

Apologies for the delay in response.. Yes resolved. It was a defective voltage regulator. Stopped by a local salvage yard, found one for a few dollars, installed, A-Ok!