What is this harness?

toxicwaste29

New member
Ive been having issues with my battery terminals not tightening enough so my dash lights are going crazy and other misc. problems. I'm trying to clean up what I have on my terminals. Does anyone know what this fuse block harness is for? It has both a positive, negative and it also has extra wire coiled near the firewall. It is factory because it has heat shield on it and it looks like its going behind the motor.
 

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This is the random coil of wire. It looks like its blue coated and it was going to nothing.
 

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Ive been having issues with my battery terminals not tightening enough so my dash lights are going crazy and other misc. problems. I'm trying to clean up what I have on my terminals. Does anyone know what this fuse block harness is for? It has both a positive, negative and it also has extra wire coiled near the firewall. It is factory because it has heat shield on it and it looks like its going behind the motor.

Do you have front seat heaters? I think it might be for those or for another factory option/accessory, if you're talking about the fuse block that's attached to the firewall.
 
I followed the harness and it is going somewhere on top of the gas tank. If that helps identify what it is for. The fuse holder has a 20a fuse
 
If that is the case why would it have factory heat wrap and also I've had this jeep since it had 4k miles so I couldn't have seen it needing on before then
 
I may be wrong here, but I don't think our JKs come from the factory with any blue wiring. That type of wire is usually for an aftermarket alarm, sound system or to run power to a flat tow vehicle or a trailer (as I'm having done right now).... the previous owner may have towed a trailer or flat towed the Jeep behind an RV and that wire may have been what supplied power to the brakes/lights, etc.... I believe Mopar does make harnesses like that, which would explain the factory heat wrap.

EDIT: here's a pic.... can't tell if it's the same thing. Mopar part number 82211156AB

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^ that is exactly what I have. I traced the heat tubing all the way to the rear. It is for my trailer pin power and ground. It then ties into my driver taillight for the rest of the trailer light functions. Im assuming the blue wire is for trailer brakes since that what it is typically which explains why it is just coiled up in the engine compartment.
 
Is the female plug at your hitch 4 pin or 7? If it's 7, you got a nice little upgrade. But even if not, you're wired for it, as you're correct about the blue wire controlling the brakes. There may have been a brake controller in the mix that was removed by the previous owner.
 
I have the 7. I was hoping for the max tow package for the bigger gears but my sheet from jeep told me I have 3.21 :grayno: It didn't mention this harness and it was zip tied to a factory harness so Im assuming it was installed after the jeep was built.
 
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