Left side brake woes

[Jesus Chrysler]

This is something that I have access to via a friend for testing, if you know someone that has one, they can be a life saver.
Power Probe PP3LS01 Circuit Tester - Electronic Testing

I own one, they are great. It's nice to be able to apply ground and 12v when you're poking around.

 

[TrailBeast]

I used 3 jumper wires with alligator clips from the light socket to the trunk latch. I've also got tail lights working properly without the additional grounds.

The light socket has definitely seen better days, though. Does anyone have a part # to reference for correct replacements?

You said light socket, but you need to ground the bulb base and try it.
The sockets can loose their ground to the housing.
Tail lights working doesn't necessarily tell you for sure that the brake light is getting the ground it needs.
Some the sockets are so sketchy about grounds that I even solder a ground right to the bulb base itself.

 

[Jesus Chrysler]

You said light socket, but you need to ground the bulb base and try it.
The sockets can loose their ground to the housing.
Tail lights working doesn't necessarily tell you for sure that the brake light is getting the ground it needs.
Some the sockets are so sketchy about grounds that I even solder a ground right to the bulb base itself.

I eliminated the socket altogether and made connections directly to bulb shell and filament contacts. Still nothing. I even tried it with jumpers straight off the kick panel connector

 

[TrailBeast]

I eliminated the socket altogether and made connections directly to bulb shell and filament contacts. Still nothing.

Ah, ok.

 

[RedFish]

The light socket has definitely seen better days, though. Does anyone have a part # to reference for correct replacements?

First... Confirm your fixtures hole diameter ( I'm thinking it is 3/4" ). Google 1157 two wire socket. You should find replacement sockets and/or renew parts for the socket you have.