1969 Truck Tail light Problem

[billrobbobjo]

I have a 1969 GMC 3/4 ton and I am having major problems with the tailights. First i had a ground problem. I fixed this by getting the Ground wires all cleaned up and they seemed to work. Every once and awhile my Break lights would get stuck on, weird things started happening. I first thought it must be the break light switch, 8 dollars later no difference. Got the new one in didnt change a thing. I called all my buddies who know a lot about old trucks and what not and they told me it must be my Turn signal switch. Pulled the old one out and put a new one in. Im currently getting my night time Running lights to work, But i still have a problem with the blinkers and my break lights. As of right now my break lights turn on as soon as I hook up the battery. I have been playing with the break light switch for the last 2 months and it doesnt seem to be the problem but something around there it seems to short out and cut around the switch and make my break lights come on. Anyone have a problem like this? any ideas to where my problem might be. This has been driving me crazy for the last 2 months and i just wanna go home in a week, this is my ride!
Its also weird when i turn my right blinker on my Break lights go out. When im in the neutral spot for the blinkers the break lights are on. When im turning to the left its how its supposed to be.
Any Help would be great! done alot of work on this thing and do not want to throw it all away because of some wires!

[Molberg]

I had a similar issue with my chev farm truck. Trailer harness wiring. Previous owner was under the back end and chopped in a complete mess. Bare connections.. Wires pieced together.... And some broken. Removed all of it and it's been fine since.

[luvbowties]

You said, "Its also weird when i turn my right blinker on my Break lights go out. When im in the neutral spot for the blinkers the break lights are on. When im turning to the left its how its supposed to be." When a sig is called for, the ts switch cancels brake lite on that side & lets flasher work it. Sounds like left side wires are correct; but sounds like wires are not properly placed at t-sig switch harness connector for right sig. Also, sounds like your br-lite switch is not completely cancelling when br-pedal is turned loose, leaving br-lites on improperly. Is br-pedal spring returning pedal to completely up and breaking the br-lite sw circuit? (Either put stronger spring on or adjust switch properly.) Check that new br-lite sw is good--new does not always mean good!
Look up wiring diag. for your t-sig sw cct & verify proper wiring at the t-signal switch: prev. owner coulda crossed wires. [Search for "Woogeroo"s posts in the 60-66 forum where he gives links to older truck wiring circuits.] Last, install a quality flasher.
Sam

[billrobbobjo]

Ok well i will give that a look over, i looked at the break light switch and it have it adjusted so it breaks the connection and goes out. When i first put in the break light switch they worked on and off until i started to use the blinkers more. I will check it with my voltage meter and see if get a current through it. I just hope i don't need to buy a full new harnessing kit for it.
Thanks guys
Robert