I've got a 1979 f-150... 4wd, engine is a 300 inline 6 hooked up to an np435 transmission (Granny low ftw) In the future it's going to be a project truck, but right now that's not going to happen due to its daily driver status...
On weekends I usually try and fix (or break) something... not really trying to get anywhere with it, just like to tinker...

Currently I'm trying to track down a wiring problem that's been bugging the hell out of me for awhile now (3-4 months)

When I turn on the dash lights, the right turn signal indicator also turns on (except for when I'm using the turn signal, then it acts normal) Sometimes the backlights on the left side of the instrument panel don't work, sometimes they do... but the 2 issues seem to be related... Currently have dash and steering column pulled apart, been poking stuff with a multimeter, I know theres a short somewhere (not in the instrument panel, it first show's up in the plug that connects to the panel... Haven't been able to find a diagram of the turn signal switch so I don't know how that's supposed to read on the multimeter), but I'm running out of ideas on where to look...

Any information/ideas would be appreciated...

*edit*

Forgot to mention that it still does this with the turn signal switch dissasembled...

 

First off are any wires cut and spliced together? I have been amazed ant what people do with wiring! If the turn signal wiring has been butchered I would replacce the whole signal assembly...it is pretty easy. Then clean the circuit on the back of the cluster, you can do this with a pencil eraser...be gentle with it, they are 30+yrs old. I had a similar problem and mine turned out to be the turn signal bulb sockets, they can be bought for about $8 each at an auto store. Since I have replaced mine all the lights have been working like they should.

 

Mine did this for the longest time. Turns out I had a ground wire come loose. I think it was on the left side near the headlight.

A lot of times when something like that happens the ground wire is the source, but its hard to be 100% sure.

 

Turn signal wiring is stock, and the circuitry on the cluster tests out ok... good idea, I'll clean it before I put it back together.

I did find a 'loose' wire, about a 4-5 inch tail that just went into the bundle and ended without connecting anything.... thought it was maybe a ground, but the gas gauge stops working if I ground it... Can't see anything else it'd connect to so I taped the end of it and left it.