Ok I posted this last night and for some reason it's not here today so I'm going to repost it.

I have a 68 C10 that has a turn signal problem. Both of the front signals blink no matter what side you turn on.

The rear lights work normally.

Here is what I have already done.
1) I have cleaned and reterminated all the grounds.
2) replaced all the fuses and checked to ensure that the bulbs are correct. Replaced flasher as well.
3) opened all of the wire looms and taped looms to check for shorts nothing found.
4) Pulled the fuse box off the firewall and cleaned and inspected, no problems there either.
5) Piggybacked in a new turn signal Switch, problem sitll remains.
6)Checked for voltage drop, IE corooded wire, bad socket etc... Nothing found there wither.

Additionally, there are no modifications to the stock harness that would contribute to the problem. It's only the front signals that has the problem.
Rear signals work perfectly.

I'm just about at the end of my rope, I would hate to take it to a shop to fix the darn turn signals. But I'm completely stumped.  

After ignoring the problem for about two-weeks I would start over (this alone seems to always work) by checking the 4-way flasher switch and wiring. '68 was the first-year for 4-ways, it was a DOT compliance thing, like side-marker lights and a few other so-called saftey features like dual master-cylinders etc.

You are picking up extra juice from somewhere, uplug the 4-ways and just about everthing else. Do this until the problem clears up, and then plug it all back in.  Anyway, this is how I would do it.  

John,

Yesterday I decided that even though the new switch piggybacked in was causing the same problem, that I would go into the colum and verify that something fishy wasn't going on. Found out that I didn't have the right bolts for the wheel puller I could see the switch but not get it out. I fiddled with it and ended up putting it all back together. Problem still existing.

So I then decided that I would go after the dash lights and see if there was any hope for the printed curcuit assy on the back of the dash. It would seem that after removeing the dash and unplugging the headlight switch (guess) that everything is now back to working as advertised. I believe that a loose plug at the headlight swith may have been the culprit. I did fine some minor oxidation at the connection on the headlight switch and the plug was not very tight in the switch. Upon reassembly and a posative attention paid to the headlight switch. Every thing is currently working as advertized. I'll certainly keep you posted.
Regards!  

Glad to hear you found the problem, electrical can drive a guy absolutely nuts!

I think the best general advice, is to disconnect everything from the system, and then add back until the problem rears it ugly head.

We had big trouble with an A/C switch right before I left for Americruise. Of course it took many hours to determine it was the switch.

Talk to you later  

check all the wireing to make shur there is no bravvcks in it that could be the anwser ok