My left tail light stops working after I've been driving my 1966 hard top for several minutes (both when using the turn signal and when using the break light). The lights work fine when the car is relatively "cold." I've checked the bulb and the tail light ground. The bulb is fine, the ground connection looks ok. Should I replace the turn signal switch next, or is it likely a different problem. Thank you all.

 

the reference to hot and cold temperatures is a little confusing. I suppose as the temperature increases, resistance in the electrical system does as well. however, it should stop working or be affected that much.

before replacing the turn signal switch- verify how much voltage it at the tail light, should be at least 10.5v (even with old wiring). because it is affected both the brake light and turn signal makes me believe it's a power source for the left side.

 

Or it could just be a bulb filament issue. change the bulb, they're cheap (PN 1157), then go after electrical demons if they're still there.

 

My 66 fastback did the same thing. I fixed it by running a difrent ground

 

How do I run a new ground to the light? Should I just cut off the end of the wire contacting the light and splice on a new wire with a new ring to attach to the bolt?
Thanks for your helpl

 

there should be a ground wire there already- just run a new wire bolted to the chassis with a screw (contacting a clean, paint free area).