Mopar Flat Tow Harness arrived

dgreen1069

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I just installed the Mopar flat tow harness yesterday. Words cannot describe how useless the instructions for this kit are. The pictures help a little but aren't a great representation of anything. I was expecting this project to take about 3 hours but I ended up working in the dark for half the install and it took 6 hours. Nothing was terribly difficult, just lots to do with little to no guidance from the instructions.

Here are a few tips:

Watch a video on installing the hitch wiring for tips on how to remove most of the interior trim pieces. The trailer hitch wiring and flat tow wiring are installed in very much the same manner.
Watch a video on removing the entire fender with inner fender attached vs following the directions and messing with all the rivets and such. This is an absolute time saver.
Watch a video on removing the rear bumper. All the videos I saw were for 2018's and the middle attachment points have changed for the 2020's. There are four bolts on each side of the bumper where it attaches to the frame plus two 10mm bolts on the bottom of the bumper on either side of the hitch.
Don't bother running the harness from one tail light to the other until you have removed the bumper. With it out of the way, it's more clear where the wiring is routed. If you already have trailer hitch wiring, some of the holes used to attach the flat tow harness are used up. It wasn't a big deal, but seeing how the trailer hitch wiring attached was helpful for getting the driver's side correct.

Use a coat hanger to fish the wiring through the firewall grommet. I tried doing this from the interior first but had better luck starting from the engine side and going inwards. I thought a flimsier hanger would be helpful but it was not. The grommet is two layers and the flimsy hanger I tried using wasn't punching through very easily. A stronger hanger made quick work of it. This part is a giant pain in the ass! Don't take the hanger off when you get through the firewall. It was helpful in bringing the wiring up towards the battery also.

Like many jobs, the first time was a giant PITA. I'm fairly certain I could knock the project out again in less than 3 hours.





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roaniecowpony

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That's too bad about the towing harness. But this thread is about a FLAT TOW harness. Still, I appreciate the post as I'm likely to install the same harness.
 

dgreen1069

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That's too bad about the towing harness. But this thread is about a FLAT TOW harness. Still, I appreciate the post as I'm likely to install the same harness.
My post may not have been clear, but I was referring to the flat tow harness. I'm setting my rig up as a toad and just did the Mopar flat tow harness. The videos I linked to were the closest I could find that show what you need to do.
 

roaniecowpony

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My post may not have been clear, but I was referring to the flat tow harness. I'm setting my rig up as a toad and just did the Mopar flat tow harness. The videos I linked to were the closest I could find that show what you need to do.
Sorry, I mistakenly thought your post was for the tow harness since the pix showed the hitch area.

On my installation of the flat tow harness, I drug the whole installation out over a week, not working on it during the week, just the weekends. While the instructions were weak, I eventually got the idea. It did take a lot of thinking about the pix in some cases. Like the wiring pin locations for the fuse holder. But it made sense in the end and my installation worked right away first time.
 

Durango

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I just installed the Mopar flat tow harness yesterday. Words cannot describe how useless the instructions for this kit are. The pictures help a little but aren't a great representation of anything. I was expecting this project to take about 3 hours but I ended up working in the dark for half the install and it took 6 hours. Nothing was terribly difficult, just lots to do with little to no guidance from the instructions.
Here are a few tips: ...
Watch a video on removing the rear bumper. All the videos I saw were for 2018's and the middle attachment points have changed for the 2020's. There are four bolts on each side of the bumper where it attaches to the frame plus two 10mm bolts on the bottom of the bumper on either side of the hitch.
Your post confirms that I did the right thing by having the dealer install my flat tow and towing harnesses - I don't have the patience you must've had!
Interesting comment about the change for the '20's - I don't know about the attachment points, but I do know I've ordered some bumper accessories for the '20 and although everything lined up, the bolt sizes were not as the accessory mfr's said they would be - the accessories were for '18 and '19 JL's, so I figured some changes had been instituted in the '20's that the accessory mfr's hadn't caught on to yet...
 

roaniecowpony

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For anyone doing this in the future, removing the rear bumper is not necessary. The whole reason they have you remove the bumper is to get access to the license plate light connector. I did this from under the bumper with a set of 10" long forceps I have had in my tool box for years. If you don't have them, get one! Also, there are long needle nose pliers that are common in tool stores that should work fine. It took me a few minutes of messing around with the forceps and a long flat blade screwdriver to unlatch the connector and plug in the harness. But it saved a lot of time.
 

dgreen1069

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For anyone doing this in the future, removing the rear bumper is not necessary. The whole reason they have you remove the bumper is to get access to the license plate light connector. I did this from under the bumper with a set of 10" long forceps I have had in my tool box for years. If you don't have them, get one! Also, there are long needle nose pliers that are common in tool stores that should work fine. It took me a few minutes of messing around with the forceps and a long flat blade screwdriver to unlatch the connector and plug in the harness. But it saved a lot of time.
I agree, it is not absolutely necessary. That said, I did find it easier to route the harness as intended with the bumper removed. Once I took the bumper off I could see how my trailer tow wiring was routed and I followed the same route for the flat tow harness. The bumper comes off fairly easily, so don't hesitate to pull it if you can't reach the license plate light with tools.
 

RayJay

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Hi All,
Just finishing up my Mopar harness install and realized that mine didn't come with any fuses. No big deal, I just need to know what size. The "quality" instructions only say I need 4 of them.

BTW, I found an easier video for pulling the rear bumper, just pull the plastic cover.
 

JLBuyer

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Sorry if I missed it, I read through the entire thread over a couple days. Is the kit part number not two door/ four door specific?
I think I’m going to get one ordered.
 

RayJay

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Sorry if I missed it, I read through the entire thread over a couple days. Is the kit part number not two door/ four door specific?
I think I’m going to get one ordered.
The harness is 4 door specific but has steps for 2 door. Too long for 2 door too short for Gladiator.
 

dapipp

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Hi All,
Just finishing up my Mopar harness install and realized that mine didn't come with any fuses. No big deal, I just need to know what size. The "quality" instructions only say I need 4 of them.
You need four 10 amp fuses.
 

JLBuyer

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Factory order JL once I finalize the configuration..
The harness is 4 door specific but has steps for 2 door. Too long for 2 door too short for Gladiator.
Does that mean I need To do a little more research and find the two door part number Or does somebody have that?
 

RayJay

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Does that mean I need To do a little more research and find the two door part number Or does somebody have that?
You can use this harness, just have extra wire to hide. Search online for the installation manual and check it.
 

JLBuyer

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You can use this harness, just have extra wire to hide. Search online for the installation manual and check it.

I think I’m just gonna stick with what I know I had a Demco kit on my 2013 sonic that worked awesome for years, never a problem. It was reasonably priced. No diodes, no relays, no fuses, no cutting, no splicing no probing with a test light or any nonsense like that. just plug into the tail lights route to the front of the vehicle, wire in your 6 way and done.
I just keep looking at that Mopar harness and for what it is it just seems way overpriced, way over engineered and way more work than it needs to be and I keep hearing of people having problems with it sprinkled throuout the site.

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iaflier

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For any of you that have already installed the Mopar Tow Harness - I have a question on the connection of the "A" wire harness to the connector shown in step 12. It shows removal of the white plastic lock that comes in the connector. Does this "lock" come all the way our and if so how is it removed? I can only get mine to move about 1/8" inches which isn't far enough to insert any of the 6 pins. Any help will be appreciated. Thanks.
Has anyone been able to get the white lock out of the plug on harness A?
 

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