Installation of 4-Way Wiring Harness on 2019 Jeep Grand Cherokee to Upgrade to MOPAR 7-way/4-Way

Updated 02/29/2020 | Published 01/26/2019

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Wiring Kit for 2, 4, 6, and 8 Brake Electric Trailer Brake Controllers

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Question:

Goodmorning, My 19 grand Cherokee didnt come with the factory trailer harness to my surprise after installing a mopar hitch and 4-7 way mopar plug. I realize that I need the kit you offer that plugs into the tail lights...my question is, do you offer an adapter that will convert the 4 way plug into the round oem so I can use the mopar 4-7 way plug on the hitch? I dont need trailer brakes or reverse lights so I will only be using the 4 prong connector...thanks.

asked by: Chad N

Expert Reply:

Since you don't have the tow package wiring on your 2019 Jeep Grand Cherokee, the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118727 is needed. This harness will connect behind your vehicle tail lights and will connect directly to your vehicle battery to protect your electronics from overload. This will give you the 4-way trailer functions you mentioned. Then if you want to use the Mopar plug, you will simply cut the 4-way plug off the end and use the Hopkins Universal Wiring Harness for Hopkins Multi-Tow Vehicle-End Trailer Connectors - 4' Long # HM40985. You will connect color for color with the included butt connectors however you will connect both white ground wires with the ring terminals to a bare metal frame connection on your vehicle. The red (12V power), blue (brake controller output) and purple (backup/reverse light) functions can remain unconnected. If you want to add those features you can simply splice into your reverse light wire behind one of your tail lights and then use kit # 5506 for the other wiring and circuit breakers needed.

expert reply by: Jason S

Erik F.

2/28/2020

I have a 2019 grand Cherokee limited and I ordered the trailer wiring harness. I installed it correctly and when I went to test I had not parking lights on the trailer illuminated. Come to realize my parking lights on the jeep are not with the bulb and are illuminated by a led strip around the tail light and is on a completely different harness which makes sense as to why there is no parking lights on the trailer. My question is, is there another harness that I would have to buy or do I have splice into the led strip harness.

Chris R.

2/28/2020

The running lights circuit on your Jeep would indeed be separate from the brake/turn signals, but the Tekonsha T-One Harness # 118727 should still work to illuminate them on the trailer. Splicing shouldn't be required at all. I would make sure the white ground wire coming from the harness is securely attached to a clean/bare metal surface. A weak ground is the most common cause for the running lights not to work since they require more amperage than the turn and brake lights. Let me know what you find and we can go from there.

Erik F.

2/28/2020

I thought of the same thing but the harness plugs into a plug that does not have parking lights. They are a totally different plug on the back side of the taillights. But if there is no signal from the vehicle to the trailer harness for the parking light then there would be no parking lights on the trailer. And there is no other plug or harness to plug into the parking light harness to make them work

Chris R.

2/29/2020

So on the driver's side portion of the T-One harness there is actually a second plug that you would use to tap into the parking lights circuit behind the tail lights. Did you make two connections on the driver's side (the passenger's side would still just have one). There is a second 2-pin connector (black) behind the driver's side tail light that you will plug the T-Connector end with the brown wire to. This should be what activates the running lights pin on the 4-Way. If you've already done this let me know and we'll continue troubleshooting.