Hey guys! I am a brand new member with a "new" 2001 Jeep Cherokee XJ. When I got in the Jeep two mornings ago, I pushed on the rear defroster and the light on the switch came on, but it never defrosted. I've since learned that when I hit that defrost switch, all three of my brake lights come on. Nothing appears out of whack with the wiring, and I have good continuity in the back glass lines for the defroster. When I put my ohm meter up to the wiring with the defroster activated, I got nothing. So I replaced the fuses, still nothing. Replaced the relay, and now have power to the defroster, so that appears to be working. However, my 3 brake lights still come on and stay on when I push on the rear defrost. Has anyone seen this before or does anyone have any ideas. BTW, just ordered a ton of parts from Quadratec, so I will posting pictures soon of my build in progress, but for now, this light thing is driving me nuts. Thanks guys!

 

Probably a short in the loom between the chassis and hatch.

 

Do you mean at the top of the lift gate when it is open, where the wires go into the jeep itself from the lift gate? I looked at that and did not see anything, but will look again. Any other ideas?

 

The break will be inside the rubber boot likely.

 

Also the ground locations are on the same panel for those. Maybe the lights are picking up voltage through the ground. Only strange part is that the harness for the right side tail light is separate and on the opposite side. Is your right side light also affected?

 

Agreed on a ground issue. A test, run a wire from bat neg back to the ground for the defrost (wherever that is), and see what happens.

 

Thanks a ton guys. I am going to try and look into the ground issue tomorrow. Both left and right taillights are both affected, so yes, that is weird. Thank you for the photo and all of the ideas. I am loving this forum. Getting ready to put Smittybuilt XRC bumpers front and rear, Defender roof rack and Quadratec Q9500 Stealth winch on...will post pics when I do. Until then, gotta figure out this defrost bug.

 

Wondering if there was any progress with this? I have the exact same issue and plan to pull apart the gate/ cargo area in the morning. Thanks to all!!!

 

Same thing but mine also would turn my rear wiper on and all my washer fluid would run out rear when applying brakes