hi, I'm having the same issues in my 87 MJ. ive swapped over a 91 ho out of a laredo i belive, donor was beat to all hell and had no doors so not 100% sure on trim level.
anyway, 91 engine, harness and dash harnes, fires up and runs good. but am having lighting issues.
before trying to hook up rear lighting all front lighting worked the way it should other than turn signals. i follow this pin guide and now i have break lights, and tail lights, but now only left running light in the front and only right turn signal in the front. and turn signals won't work with brake lights on(the just stay on and won't flash)
i have been working on lights for about a week and at my wits end with this. i don't understand how lights went from working to not and only working in certain modes.