1966 GMC brake light help

[66gmckid123]

I don't really post much, but maybe I should. I've got a puzzling question for you guys. I have a 1966 gmc long bed and I cannot get the rear brake light on the driver side to work. It has worked for the 5 years I have had it. I replaced the bulb, which was burned out, to not avail. I checked and cleaned off all the grounds and still no brake. I am thinking that the brake light switch is no good and was wondering what everyone's thoughts were. I shook that switch and my dad said the brake light came on for about a second. So maybe this is the problem, hope you guys can help me out. And I still have a turn signal to that side.
Thanks!

[MikeN]

Honestly, 9 times out of 10 brake light problems do turn out to be ground related. I removed the bed on my 64 to replace the wood decking, and never could get a decent ground after that. I ended up fabbing a ground wire.

Try your turn signal on the side with no brake light. If it doesn't work either, you proably have a ground issue.

EDIT: My bad, I re-read you post and you do have a turn signal on that side. I still don't see how it could be the brake light switch. If the switch was bad, neither side would work.

[tenni126]

If I'm not confusing this with any of my other old crap, the taillight bulbs are grounded to the body through a sheetmetal screw that secures the taillight bucket. I added a seperate ground wire on each side to help. *BUT* you say you have turn signals all the time, so the ground is good enough. On most of these old trucks the turn signal switch can cause brake light trouble, as the wiring goes through there for priority when the brake lights are activated while the turn signal's flashing. If the brake light switch was bad it'd be both sides. Same with the bulb...same filament for brake and signal, so again, I'd suspect the turn signal switch.

[66gmckid123]

Thanks for the help, it was the turn signal switch.