Mopar Flat Tow Wiring Harness Not Working

[claytucc3]

Hello all, I just installed the Mopar 82216358AB Tow Vehicle Wiring Harness on my 2026 Rubicon X. I quadruple checked the wiring and everything is as it should be. I tested it using my F150. None of the lights on the Jeep are working. I am getting voltage to the fuse box on the Mopar wiring harness. Has anyone had similar issues or suggestions? I'm at wits end.

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[2020JLRKen]

Hello, I'm having the same issue with my 2020 2 Door Rubicon. I recently bought it pre-owned from a Jeep dealer. I ordered Mopar part number 82216358AB online from ebay and did a self install, like you I have voltage at the fuses under the hood, but no lights. I removed the tail lights and checked for voltage at the relays, and I was getting 12V on the green. I started wiggling plugs, swapped 2 of the relays, started the tow vehicle (voltage dropped to 11V) and re-seated the plug at the trailer hitch, and the tail lights started working!!! I then re-assembled the Jeep, tested again, now I get nothing. Tried everything. I saw a post online where someone had same issue, spent 11 days at dealer, for dealer to say relays are bad and can't find replacements. I drove the Jeep to Home depot, I got a msg on the dash the RR flasher was out, it was blinking quickly, I put the hazards on and it went back to normal. I'm starting to think it has something to do with relays in the harness behind the tail lights, there must be a bad batch circulating around. Have you made any progress? Also at wits end, supposed to take a trip in a week. thanks in advance

 

[azjl#3]

Just saying, another reason to go harbor frieght wiring and led tailights.

 

[claytucc3]

Hey man, I didn’t update this thread because it didn’t get any traction. It turns out the issue was with the ground from my tow vehicle to the Jeep. The Jeep uses the power from the tow vehicle to power the lights. If the ground isn’t great going through the 7 pin to the 6 pin it can cause issues. If you have another vehicle with a tow plug, you can try testing it. I never assumed this would be an issue as my tow vehicle had no issues with previous trailer lighting.

 

[2020JLRKen]

This makes alot of sense since I only pulled the Jeep up behind my F150 just close enough for the plug to reach and test, never actually hooking up the tow bar and thus creating a good ground between the two. Thanks for the tip, will try out tomorrow and report back. I had thought the white wire was ground and good enough.

 

[2020JLRKen]

Just saying, another reason to go harbor frieght wiring and led tailights.

I'm still resisting, I'm in too deep now!

 

[2020JLRKen]

OK, so I ran a ground wire from the negative terminal on the jeep to a bolt in the Bed of my F150, turned the hazards on in the F150, nothing at the Jeep. I then starting experimenting, turning lights on/off, hazards on/off, still nothing while having a 2amp trickle charger on the F150. Then, in desperation I started the engine on the F150, and suddenly everything came to life! hazards, running lights, etc all started working on the Jeep. Wonderful. I then removed the ground wire, and everything still remained working. Even Better but here's the head scratcher. I then shut the engine off on the F150, hazards and running lights shut off on Jeep, but remained on with F150. My Roadmaster Tow Bar has LED lights, they also stayed on from the F150. WTF? I then started the F150 back up, nothing on the Jeep. Unplugged the 7 way, plugged it back in, then Jeep Lights started working again. It's like I have wire Gremlins. So to summarize, If I start the engine on the Tow vehicle, and fiddle with the 7 way, I can get it to work, but as soon as the tow vehicle engine is shut off, you have nothing on Jeep. Way to go Mopar. Best $600 I've spent in a while.

 

[claytucc3]

I think it has more to do with how the F150 is wired than the Jeep. My F150 has no issues running lighting on my Travel Trailer but doesn’t work on the Jeep. When I plugged the Jeep into two other vehicles (My other 2024 Wrangler and an older Chevy pickup) the lighting system on the Wrangler worked perfectly.

 

[diversark]

My issue is with the battery on my toad. 2023 wrangler 4xe with Blue ox setup. Every time i tow it the battery dies. Stuck wherever I am until I can recharge and restart. Can’t even get out of Park to push it. Do I add a cutout switch to the battery? Add an inverter to keep the battery charged then just run the lights off the RV? Just got finished paying an off road specialist to wire the toad battery directly to the RV. 7 bills and still no joy. Help

 

[claytucc3]

You should have hot 12v going from your RV to your road vehicle. Both have to be correctly wired for it to work. Not all motorhomes are wired from the factory with a hot 12v lead.

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