The wiring diagrams can be found in the factory service manual:
https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
I recommend opening it on a computer or tablet; it’s a very large PDF.
The sidemarker bulb grounds through the inactive filament on the front turn signal bulb. So if the front turn signal bulb burns out a filament, sometimes neither bulb will work.
Do the running lights work? Does the sidemarker flash when both the parking lights and turn signals are on?
The sockets sometimes get corroded and fail to make good contact. I had to replace mine. Fortunately the front sockets are like $10 on RockAuto and are very easy to replace.