1968 Turn Signal Issues

[Motoboy]

I'm just trying to narrow down where to start my troubleshooting. I have a 1968.

Symptoms:
Headlights and running lights work
Brake lights work

Right turn signal works
Left turn signal works with lights off, but right also flashes but dim
With Lights on right still flashes, but left doesn't, just stays solid.

Should I start looking in the turn signal switch or headlight switch, or somewhere else?

[flyboy2610]

I would first check all the grounds to be sure they are solidly connected to good metal. Bad grounds can make the lights do some pretty funky things.

[Calfdemon]

Definitely sounds like a bad ground somewhere in the circuit.

[Motoboy]

Ok, I'll check all the grounds tonight, and report back.

[Motoboy]

ok, found the issue. Part of the tail light harness was fried. About a foot of wiring was affected, but the rest looks good. Is it wise to just replace the burnt section, or is there an economical replacement?

[68RGR]

Without knowing how many wires or connectors are involved in the section that is defective, it's a little hard to say. You COULD go to a junkyard and try to find an appropriate piece to replace the section. Years ago, I replaced 20+ wires in a wiring harness that ran all the way across the dash of an import. I used a piece of mobile telephone cable that had that many wires in it. Worked out well.

You could use individual wires and wrap them with tape when done to give them some protection. I prefer to solder and heat shrink the joints because solder gives you a more reliable connection.

By the way, could the wiring damage be due to faulty trailer wiring? I ask because it seems so many people run into wiring problems that can be traced to wiring for a trailer. It's only four wires but, somehow, they manage to mess it up! Then, the next (or the next or the next) owner gets to deal with it.

[Motoboy]

The harness was actually unmolested and the truck never had a trailer behind it. There is a rubber block- maybe used to protect the wires?- that's the spot where the wires melted. Its right after it comes out of the frame where the taillight harness connects to the front harness. I guess it wouldn't be too hard to splice in new wire and tape it all back up. The original connectors are still in very good shape as well.