I need help finding an electrical short in my 2011 JKUR. The M18 fuse which powers the rear passenger running lamp, licence plate light and, the passenger parking light keeps blowing when I replace the fuse and turn on the lights. I cant seem to find a loose wire anywhere and I haven't added anything electrical (Lights, winch, etc.) that runs through the main fuse box. Has anyone had a similar issue or have any advice? Any help at all is much appreciated!

 

Free bump to the top for some help, cuz this seems like it's gonna be a PITA to locate.....and hard to drive at light with no rear running lights. There's not really any place that the loom running to the back would get bent/crimped/worn that I can think of, and I've had mine apart all the way from passenger foot well to the rear. This is randomly started? You have done nothing at all recently? Just one day it was working, next it was shorting out?

 

Yeah it just happened. At first, I thought it was just a light bulb (before i noticed the front parking light) i then replaced it of course to no avail. So then I replaced the rear wiring harness for the passenger brake, running and, turn signal..... no luck. so i checked the fuse and it was blown, replaced the fuse and light came on for a few minutes..... fuse blew again and now blows immediately when i replace it and turn on the lights.

 

Man, chasing shorts is such a pain in the rear. My suggestion is remove all the bulbs from the light assemblies that run from this fuse. (Be sure to buy a stock of said fuses)

Power on the circuit ie. turn on the lights. Does the fuse pop? No? Then add back in one bulb. Rinse and repeat till you can isolate it to at least one assembly/circuit. I'm going to look over the wiring diagram for this circuit and chime back in later.

Sadly, I cannot get the wiring diagram to open. IE8 keeps giving me some type of SIE error. Not sure on that going to poke around.

 

Wouldn't the fuse blow whether or not the bulb is in place? The shorted path to ground has to be before the bulb in order to blow the fuse.

 

I agree Ronjenx. I've seen some shorts that have been caused by bulbs themselves in the past. I am no super electrician, I know enough to not zap myself too hard! Sometimes I over think my troubleshooting instead of following KISS (Keep It Simple Stupid) and this can give me more of a headache, but hey I learn something and that's the best part! Now I am really second guessing any advice I was going to give.

Okay found a PDF although for a 2009.

I would try this. First, being it was my Jeep.
Remove all lamps associated with M18 fuse. License Lamp/Right Rear Park Lamp/Right Front Park Lamp/Right Front Marker Lamp. Do any lamp sockets look corroded? If so clean it. Do any bulbs look questionable? If so get a new a one.

You can google 11 Jeep JK wiring diagram (or click that <---).

Do your best in trying to isolate the circuit from the front lights to the back lights. Good luck.

 

It would be interesting to know if the fuse would blow if you first turned the lights on, then put a good fuse in the slot?