7 Pin Towing Harness (Install & Issue)

wbgoode77

New member
Bought and installed a Mopar Trailer Hitch Wiring Harness (8221 6359 AA)...now I've got 3 errors (Check Engine Light is on, Service Electronic Stability Control, Service Electronic Throttle Control). Essentially the jeep is inoperable...will only accelerate at a snails pace.

Has anyone installed the towing harness and ran into same issue? I've gone back through it several times to insure all connections are hooked up correctly and even removed all connections (back to stock), and I still get the service lights. Fingers crossed someone has a simple fix...anything short of having my jeep towed 50 miles to the closest dealership, a hefty bill, and total waste of several hours will be an improvement!

Thanks in advance and hope to see a miracle soon. :)
 

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CalSgt

Hooked
Did you install a brake controller at the same time? I have heard rumors that the JL's do not cooperate with added brake controllers for some reason.

I installed a Reese trailer wiring kit with no issues, it just plugs inline with the taillight harnesses. Tied it into a 7 way plug and included 12v from the battery and spliced it into the backup lights since that is not a standard option on trailer wiring. I pulled a wire for a brake controller while I was at it but don't have brakes on anything I tow with the jeep at the moment so it has never been hooked up.
 

wbgoode77

New member
Did you install a brake controller at the same time? I have heard rumors that the JL's do not cooperate with added brake controllers for some reason.

I installed a Reese trailer wiring kit with no issues, it just plugs inline with the taillight harnesses. Tied it into a 7 way plug and included 12v from the battery and spliced it into the backup lights since that is not a standard option on trailer wiring. I pulled a wire for a brake controller while I was at it but don't have brakes on anything I tow with the jeep at the moment so it has never been hooked up.
I haven't done the brake controller yet...suppose to this weekend. Fingers crossed it doesn't further complicate things!
 

jeeeep

Active Member
is this the 7 pin harness? doh, 7 pin in the title lol
I installed the RuggedRidge 4 pin and it was straight forward and didn't have to deal with pinning the connectors like on the Mopar kit. possible you have a ground from a pinched wire?
Also, the fuse lead on the 7 wire is supposed to be connected to the 1st lug on the fuse panel, not direct to the battery like the 4-pin connector; not sure why it matters

Quadratec has a good video on installing the Mopar kit:, it helped make my Rugged Ridge choice lol

I also ran my battery power line in a protective sheath along the passenger side under the tub and zipped it to the existing wiring, no need to remove any fenders, trim etc...

 
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wbgoode77

New member
Any chance you shorted something and blew a fuse?
Great advice! I checked the fuse that coordinates with "Stability Control" (F34) and it was fine...couldn't find which fuse is for Throttle Body?

Any good advice for checking all fuses...is methodically one-by-one the only route?
 

jeeeep

Active Member
if it's like the JK, most errors take several key cycles to clear out or, disconnecting the ground for 20 minutes resets; in the case of the JL, 2 grounds
 

nbunga

Caught the Bug
Great advice! I checked the fuse that coordinates with "Stability Control" (F34) and it was fine...couldn't find which fuse is for Throttle Body?

Any good advice for checking all fuses...is methodically one-by-one the only route?
Depending on how the fuse block is laid out , sometimes you can use a flashlight and shine through the fuses to see the elements without having to take them all out.
 
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