???Having trouble getting my tail lights to work properly. Checked the ground several times. When I hit the brakes the left tail light goes out. The right one is ok.I think that it might be in the turn signal switch. That is my next step.

I ran into the same problem when I pulled my car out of winter storage. It turned out to be a bad socket on my far right bulb. When that happens, all the other running lights and turn signals act weird. It only does this on my CS. ( my other stangs have a different tail light harness)
Check all the sockets carefully for corrosion or out of round. Hope this helps. Nick

I used steel wool to clean each socket when I put my car back together. I haven't had any problems. Hope this helps.

Russ

;DThanks for the response , that was my trouble. That's odd because when I hit the brakes the left light would go off. When one would flash the other one wouldn't. I had all of the lights cleaned about a year ago but I stored them in the basement. :-\

For what its worth, I've had to clean my connections every spring for the three years to keep them working properly. But not nearly as bad as the first time. Anyone got a solution on how to keep the contacts fresh?

Just keep doing what you are doing bish. Spray a little white lithium grease in them to keep the moisture out. It will keep them from corroding quicker. Nick

Nick,
Thanks for the tip!