I recently got an 03 xj8 running after sitting since 2020; had a bad fuel pump. Problem is it seems to have amassed a small list of electrical problems such as the radio being out, no abs, and most importantly being no rear tail lights at all breaks, turn signals, fog lights, ect are all gone but strangely enough no warning pops up for the lights on the dash. I would assume wiring loom but the fuel pump which runs from the same harness is fine albeit it runs off a paper clip but still it has power too it. What else could be wrong? Side note it always had finicky tail lights in terms of the night time bulbs I usually had to use the fog lights but never this much was wrong

 

Tail lights comes out pretty much from the BPM. That also reads the bulb current. I'd start by checking voltages and grounds of the bpm with load.