1997, my left tail light is not working, but the signal, 4 way, and brake are. Right side all work fine.

I checked for voltage and none of the 3 wires at the socket have power when the headlight switch if fully extended. As I said, the right side works fine.

What/Where do I look for next?

 

Check the socket itself.

 

Socket is fine until it comes to parking lights, then no power. There is no power in any wires at a test area ahead/before the socket either

 

Normally, if one works and the other does not, either the socket,bulb or the plug where the wires split off is the problem. There are two elements in the bulb as I'm sure you are aware of. Just because the brake light,hazards or directionals work. Doesn't mean the P lights will. They use a different element in the bulb.

 

tried new bulbs too...same problem.

Where do the wires "split off" on a 97 1500 ?

 

You have to follow the harness along the frame. https://dodgeforum.com/forum/2nd-gen...n-rams.htmlGet a Haynes or download this . Either one will help a lot.