I have a 96 Z28 that the left rear turn signal is intermittent. It had stopped working all together so I checked the bulb, the glass part was loose in the base so I replaced it with a new bulb, started working, I thought great quick easy fix. After a short drive it stopped working again, the socket looked pretty bad so I got a new one and replaced the socket, again it worked, super again an easy fix. Another drive and and it stopped working again. I thought maybe a ground problem but if that were the problem the running element wouldn't work either so I ruled that out. Does anyone have any ideas I'm fresh out.
Reading through the forum this seems to be a common problem.

Thanks in advance for your ideas.

 

is the front one working on that side

 

Forgot to add that, the front works fine.

 

get the volt meter out and start tracking. test to see if power is getting to socket and work to the front.

 

Got a helper today to watch the rear lights. No turn signals or brake light on the left side. After seeing that I'm pretty much convinced it a bad ground.

 

Hopefully so.
If it has tail light, then ground is good.

 

OK the saga continues. Everett good point since the running light works it's not a ground issue. However I did find something very interesting, when it's not working. i can give the light assembly a good smack and it starts working, also if it's not working as soon as I take the 2 nuts off inside to remove the light assembly it starts working. This is about to drive me crazy and believe me it's a short drive.

 

bad bulb or bad connection in the area of the socket.

 

Actually the tail light filament can appear to work normally even with a bad/open ground. That's because it can get a ground through the other filament and the bulbs in parallel with that one. It doesn't work well the other way because the tail light filament is much higher resistance than the turn signal filament.

 

If you play the odds its either a bad ground (just run a jumper wire to ground to test) or a bad socket.

Keep in mind just because the issue shows up in the tail light does not mean 100% that the problem is there. Although hitting and changing symptoms screams bad socket or bad bulb to me. I have seen defective bulbs have mechanics running in circles.

All of the above assumes that no one added a trailer connector. 90% of the lighting issues I have repaired where caused by aging trailer connectors