So I got around to splicing and trying to repair the harness that runs the running lights on the back of my 98 XJ.
Before the accident both running tail lights worked. when I had to replace the rear tail light, pulling it out of the assembly broke a corroded pin inside the harness connectors. So I went around and splice both the broken wires to a spade connector as you can see in the pictures.
However, now only the passenger rear running light turns on when you engage the lights. I checked the driver side rear bulb and it looks good. (Please forgive the crappy splice job, its literally my very first electrical splice in my entire life
Up to this point I had to use magnetic tail lights so i wouldnt get pulled over.

The extra wires I sourced from a junkyard Jeep connector behind teh tail light assembly




Anyone got any ideas?

 

I cant work out exactly what your problem is, but you do seem to have gone about things the correct way

You admit little electrical knowledge

You need a 12V automotive test light to probe around looking for 12V. Dead easy, cost $5-10, buy one from nearest auto parts store

A multimeter will work if you dont have a test light

here is some resources

FSM Downloads awg - Jeep Cherokee Forum

 

I put the one spade connector on the other spliced wire and vice versa, Both lights now work :] Yay!
So glad i dont have to do any of that!