Topic: 65' fog lamp circuit breaker fault

[jwc66k]

Here's a better wiring diagram of the fog lamp circuit. The switch is special in that it combines three connections, it adds the tail lights and license plate lamp to the fog lamp circuit. This add about 2 amps of current to it. With the 5 amps of the for lamps, the circuit breaker now has at least 7 amps going thru it.
As Charles said, the switch is a potential problem area. Now for the bad news. There is no replacement as the 65 and 66 switches are wired different at the connector.
Other potential problem areas are the five grounds (which may include the lamp housing both internal and external), each contact (corrosion after 50 years) or possibly a worn spot on the wire that is called a "short".
Jim

[Hipo giddyup]

Thanks so much for the diagrams. My headlight switch is NOS and I have no issues at all with charging and headlight usage , just this issue once the fog lamps are used. I will check the breaker first, then move onto each ground..

[sgl66]

To help narrow it down, you may want to disconnect the rear lights to remove them from the circuit and see if the fog lights still trip the breaker.

Once you're able to get ohm readings, post them and one of us can get a comparison for you.

[Hipo giddyup]

Finally got some time to troubleshoot this. I started by simply make sure I had a good ground where the breaker attached under the dash. I used a star washer for extra insurance and made sure everything was tightened up. I ran the lights on for ten minutes without issue. If The breaker trips again I think I will try and find a Nos version. All other grounds looked great and again, no other issues until I used the fog lamps . I'll be keeping my fingers crossed. Thanks again for all the replies!