Left Brake Light Not Working

[Joe Flanagan]

I have dual filament bulbs in my tail lights. Tail lights work as brake lights and directionals. When I apply the brakes, the filament for the left brake light doesn't light. With the tail lights on, if I hit the brake, the left tail light goes out (no brake light). When I turn on the left directional, the tail light filament blinks on and off instead of the brake light filament. I checked and triple checked that the bulb is indexed correctly. I checked, cleaned, and tightened the connection between the socket and the tail light assembly. Pig tails are in good shape. Junction block in trunk is in order and connections are tight. I checked both contacts in the left tail light socket with a volt meter. Neither one is getting anywhere near 6 volts. Right side socket checks out fine. I switched the bulbs left side to right and the problem is not a defective bulb. The weird thing is that although the right side light works fine, I only get three volts at the junction block in the trunk. 

How this all developed is that I washed the car and discovered that the trunk leaks through the bolts that attach the tail lights and the rear fenders (the original rubber gaskets are still there but ineffective). I removed the tail lights and applied an auto window sealer around the bolts (black ribbon-type stuff made by 3M). I was thinking this might have created a grounding issue but it had no effect on the right side light. Any ideas what's going on? 

[Plymouthy Adams]

are you sure that with the paint, sealer and gasket and oxidation from water intrusion is not causing for a poor ground..this screams poor ground connections...run you a good ground wire from the socket or socket bracket to body ground..ensure also that your car has a good engine to chassis to body strap in play also and these connections have not been compromised..

 

PS and for giggles and 'be sure you know" do a input test of voltage to the brake light switch and compare that to the output voltage when switch is activated..

Edited May 22, 2015 by Plymouthy Adams

[plymouthcranbrook]

On my 52 the right rear turn signal doesn't work. Once did, now not. Brake and tail lights work. Ground good. probably a broken wire. You might want to check into that with a continuity tester.

[greg g]

Run a separate ground wire to see if it is a poor ground issue.

[Joe Flanagan]

Thanks, everyone. It looks like it was a ground problem. I made up a ground wire and the light seems to be working normally now.