I have a 1986 IROC Z28 Camaro. Yesterday I took apart and replaced my backup lights. About once I had put the new bulbs in, it started to lightly rain, so I hurried up a bit and put it all back together before it got worse. It rained all yesterday and night. Driving the car last night, I don't remember anything wrong, but this morning when I put either turn signal on, the dash lights (and I tested later) the actual turn signal lights stay constantly lit up, except when I turn the wheel, so it flashes once then turns off after the wheel is far enough. The lights in the back seem very dim, so much so I can hardly see the brake or turn signal bulbs flash when I put the hazards on (they work). Has anyone got a clue on what could have happened? I'm going to tear apart the rear lights again, maybe I bumped something, but I never touched the turn signal bulbs, just the backup ones, and they do flash, but only once when I'm turning.

Update: Tested when dark; rear turn signals don't turn on at all, probably is related to them not blinking. The new backup lights were dual filament, maybe I put them in 180 wrong and that is somehow messing everything up???

 

Back up & signal are single filament, only brake is dual.

 

I wondered about that when the local parts guy told me those were the bulbs to be used, but figured maybe they only used one filament or something and were the equivalent. I still don't understand how they would mess up the turn signal lights, but today I'm going to take the rear lights back apart and figure this out.

Edit: I don't know what I was thinking, but the lights I bought were only single filament, but the ones in the turn signal bulbs were dual filament (must be a bulb that worked but isn't the exact correct one that P.O. installed), but it works fine.

 

Solved! The problem was a bad ground; when I removed the back interior plate of the trunk, sometime afterwards or then a ground wire connected to the contacts on the trunk lid and where it touches had broken off. This wire must also be connected to the rear lights, and is what caused all the symptoms; dim lights, turn signals not flashing (because there wasn't enough current passing through to make the thing work), front lights working but back ones not really/barely. Back up lights still don't work, but that's something else entirely; contact in the shifter needs adjusting.