Well, had a fuse box burn out a bit, blinkers stopped working, bypassed that fuse with external one. Dome light fuse blew so i replaced it. Now my jeep will only start when my door is open (dome light is on) or when i manually turn on the dome light with the switch built into the headlight switch. How does this happen?? Anyone have any ideas??

 

Probably because "the fuse box burn out a bit".
Have you considered replacing the fuse box and associated harness?
Filling out your info insofar as year etc. would be helpful too.

 

Free theft deterrent, why fix it?!?

Yea, the fried fuse box is the likely culprit. If there's a crank fuse it's wires have probably crossed to the dome light wires.

 

Its a 1990. Went through the fuse box already. Everything is back to normal except the issue. Any ideas why 12v supply to dome light interferes with ignition? Would have to be in circuit past headlight switch according to the schematic, but i dont see anywhere they run into each other

 

Your ignition switch is bad. You have contacts making contacts with other contacts you did not approve of as the owner. lol

 

This sounds just like what they call AND LOGIC in simple terms it is this and this has to be on for it to work.Why not look at both wire colors and the wireing diagram to see if they match up.

 

I doubt there's any point where the dome light power should combine with the ignition switch. Apparently something happened were the wire for the dome light is now powering the ignition switch, but that also seems odd unless it has more than one power feed. Since you have a schematic see if there are more than one power feed to the ign. switch. If there's one to power the start circuit and another to power the run circuit, the start circuit is where the problem lies. Somehow somewhere in the system it appears the ignition switch lost incoming power and the dome light power got crossed over to it, I'm guessing the same incident that caused the fuse box burn-up.

 

Maybe I'll check my grounds. Could be faulty and grounding through the dome light ground, assuming its on. Maybe... Guess ill go hunting for a bit

 

If the domes are triggered by 'turning on' the ground then you're on to something there that I hadn't thought of. Still can't figure out how or why that ground would be related to start circuit.

 

Is this a '90 XJ? I see SJ in "your vehicles".