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Price: $77.20

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TrailerMate Custom Tail Light Wiring Kit for Towed Vehicles

Item # TM781117

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Our Price: $77.20

Tow Bar Wiring

Confirmed To Fit

2012 Jeep Grand Cherokee

All Models

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trailermate tow bar wiring custom tail light mount kit for towed vehicles
trailermate tow bar wiring harness custom tm781117
trailermate tow bar wiring harness custom
trailermate tow bar wiring plugs into vehicle tail light mount custom kit for towed vehicles
trailermate tow bar wiring plugs into vehicle custom tail light kit for towed vehicles


  • Wiring Harness
  • Plugs into Vehicle Wiring
  • TrailerMate
  • Custom
  • Tail Light Mount
The best technical support and full tow bar wiring installation instructions. Lowest price Grand Cherokee tow bar wiring guarantee and expert service. Jeep Grand Cherokee, 2012 tow bar wiring by TrailerMate are available from For expert service call 800-298-8924 to order your TrailerMate Custom Tail Light Wiring Kit for Towed Vehicles part number TM781117, or order online at

2012 Jeep Grand Cherokee - TrailerMate Custom Tail Light Wiring Kit for Towed Vehicles

Quickly and easily connect your towed car's lighting system to your RV to activate the signal lights required for towing. This custom harness plugs directly into your Jeep Grand Cherokee's existing wiring - no cutting or splicing required.


  • Lets you connect your RV's tail, brake and turn signal lights to your towed Jeep Grand Cherokee's lighting system
    • Provides 4-way flat plug at front of towed car to connect to motor home
  • Plugs in quickly and easily - no cutting or splicing of wires
    • Connection points are located behind your Jeep Grand Cherokee's tail lights
  • Helps safeguard the towed car's electrical system by preventing overload with built-in diodes
    • Additional diodes (sold separately) required to eliminate electrical feedback
  • Won't interfere with electrical system when towed car is not hooked up to RV
  • Provides connection point for 4-pole flat wiring harness at rear of towed car
    • Tow a trailer behind your car when it's not being flat towed
  • Custom designed for your Jeep Grand Cherokee
  • Includes wiring harness, mounting bracket and 4-flat extension loop for hookup
    • Brake light relay (RM-88400 - sold separately) may be required if used with supplemental braking system
  • Limited lifetime warranty

Wiring Your Vehicle with TrailerMate

Typically, wiring your car for flat towing is a tremendous chore. You have to position and mount multiple diodes beneath your car and then splice into the car's wiring. Before cutting and splicing, though, you have to use a circuit tester to identify each wire. This must be done for the wires carrying signals from your running lights, brake lights, and both turn signal lights. And don't forget to jump the diodes so that the running light signal is sent to both sides of your car. could just plug in the TrailerMate wiring harness. This custom-fit system plugs into your Jeep Grand Cherokee's existing wiring harness, which is located behind your car's tail light assemblies. No cutting, tapping or splicing is required. The wiring around the plugs is encased in durable convoluted tubing, making it easier to handle and safer to route as well.

After plugging in the wiring harness, use the included bracket to mount the 4-way flat connector at the front of your towed car. Then hook up to your RV with the supplied wiring extension, and you're good to tow. Note: The extension included with this system requires that your RV have a 4-wire flat trailer connector. If your RV has a 7-pole round connector, or another type of connector, then an adapter is required.

Do You Need a Brake Light Relay?

Because your Jeep Grand Cherokee has a combined lighting system - wherein the brake signals and the turn signals are carried on a single wire - a brake light relay (RM-88400 - sold separately) may be required if you use a supplemental braking system with your towing setup. A supplemental braking system depresses the brake pedal in your towed car every time you apply the brakes in your RV. So, if your towed car's brake lights illuminate when the brake pedal is pressed and the engine is off - as is the case when towing - then you need to install a relay to ensure that the lights on your towed car always act in accordance with the signals sent by your RV via the wiring harness. Without a relay, the brake signal from your towed car will override the turn signal sent by your RV when you slow down to make turns, creating a potential hazard.

T-Connector Function for Towing a Trailer

When you're not flat towing your car, the TrailerMate wiring harness can remain on your Jeep Grand Cherokee; it will not interfere with the electronics. And if you ever tow a trailer with your car, you'll be wired and ready. The TrailerMate system comes ready to accept 4-flat wiring (TM85330 - sold separately) at the rear of your Jeep Grand Cherokee so that you can hook up a trailer quickly and easily. Just plug in the add-on 4-way trailer connector, and you're good to go.

781117 Trailer Mate RV Tow Harness for Towed Vehicles

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Video of TrailerMate Custom Tail Light Wiring Kit for Towed Vehicles

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for TrailerMate Tow Bar Wiring TM781117 Review

Today we're reviewing part number TM781117 from TrailerMate. This is a custom taillight wiring kit for towed vehicles. This part number is made specifically for the Jeep Grand Cherokee beginning in model year 2007. Using the Fit Guide will help you determine whether you're particular vehicle will work with this kit.This part provides an easy way to give power to the brake light and turn signal in your towed vehicle. You don't have to do any cutting or splicing it's a simple plug in installation. Let's start with the driver's side.

At the rear of the vehicle you should remove the cover over the back of the taillight and locate the wiring harness behind the taillight. Disconnect that and plug in these two connectors into your driver's side wiring harness.You'll notice that the driver's side wire has a yellow wire right here. Then you do the same thing on the passenger side. The passenger side has a green wire where the yellow wire was on the other side. Do the same thing, disconnect the wiring harness and plug these two connectors in to the wiring harness.Now you'll notice there's a third connecting wire at the rear.

What this is for is it enables you to install a four-way at the back of your Jeep Grand Cherokee for when you want to tow using that car as the tow vehicle. In order to make this operable you will need to purchase part number TM85330, that's sold separately. It's the TrailerMate custom taillight wiring kit with a four-pole flat trailer connector.The third thing you want to install after you plugged in your drivers side and passenger side wiring harness is your ground wire and this should be mounted on a clean, unpainted metal surface using one of the self-tapping screws that's provided in the kit. You've installed three things and then the next thing you want to do is run the long power wire, right here up to the front of your vehicle.You can secure it to the frame under your car using the included cable ties. Once you get the power wire up to the front of the vehicle you'll see that you have a four-pole here and you need to mount that.

A mounting bracket is included. You see two holes and you have two self-tapping screws for that. You see the slot in the front, all you do is slide the four-pole into the slot and then it's mounted at the front of our vehicle.Then you have also a four foot extension loop. This is included in the kit. Some kits don't include extension loops but this one from TrailerMate does so that's convenient.

You want to connect the four-pole that you just mounted to the four-pole on the extension loop like that and then the extension loop hooks up to the four-pole at the back of your RV. Now if you happen to have a seven-pole behind your RV rather than a four-pole you will need to get a seven-way to four-way adapter and we do sell those at you're all hooked and you're ready to go. Please note that this kit will prevent damage to your Grand Cherokee's electrical components that might be caused by electrical feedback from the RV because it has built in dyads that safeguard the wiring. Also it will not interfere with the electrical system on your Cherokee when it's not hooked up to an RV. If by some chance you use a supplemental braking system you might need to get a brake light relay.In that case look at part number RM88400 sold separately. There you have it for the TrailerMate Custom Taillight Wiring Kit for your towed Jeep Grand Cherokee.

Customer Reviews

TrailerMate Custom Tail Light Wiring Kit for Towed Vehicles - TM781117

Average Customer Rating:  5.0 out of 5 stars   (2 Customer Reviews)

Quickly and easily connect your towed car's lighting system to your RV to activate the signal lights required for towing. This custom harness plugs directly into your vehicle's existing wiring - no cutting or splicing required.

- TM781117


Ordered a tow hitch and base plate plus the wiring harness, people were great to deal with a and my order was shipped right away. Tow hitch and wiring was easy to install, the whole experience made me a return customer. Thanks Etrailer 63705

- TM781117


All works great. 352001


Ask the Experts about this TrailerMate Tow Bar Wiring
Do you have a question about this Tow Bar Wiring?

  • Parts Needed to Flat Tow a 2014 Jeep Grand Cherokee
  • For a Blue Ox base plate kit for your 2014 Jeep Grand Cherokee you will want the Blue Ox Base Plate kit # BX1128. For a wiring solution I would recommend the TrailerMate Tow Bar Wiring kit # TM781117, this kit plugs right in line with your taillight wiring and allows your tow vehicle to control the tail light functions of it. For a Curt trailer hitch I would recommend the Curt Trailer Hitch # C13182. I attached an install video and installation instructions for you to check out also. You...
    view full answer...

  • Wiring 2011 Jeep Grand Cherokee for Flat Towing
  • The easiest permanent wiring alternative would be the plug and play TrailerMate # TM781117. This wiring harness would plug inline between the vehicle wiring harness that feeds the taillights and the taillight assemblies. This wiring option can be installed without cutting or splicing into any of the existing wiring. To view these items, click on the provided links. We have some very helpful FAQ articles about flat towing that I'll link you to.
    view full answer...

  • Does TrailerMate Tow Bar Wiring Harness Activate All the Rear Lights on a 2013 Jeep Grand Cherokee
  • Yes! The TrailerMate tow bar wiring harness # TM781117 will activate the brake lights, turn signals, and running lights when those circuits are activated on the motor home. Because your 2013 Jeep Grand Cherokee has a combined lighting system (the brake signals and the turn signals are carried on a single wire) a brake light relay, # RM-88400, may be required if you use a supplemental braking system with your towing setup. A supplemental braking system depresses the brake pedal in your...
    view full answer...

  • Recommended Base Plates and Accessories for Flat Towing 2012 Jeep Grand Cherokee Behind a Motorhome
  • It looks like you're on the right track with the Roadmaster # RM-521440-5 but I'd recommend the Roadmaster # RM-155 lighting kit, because it will remain completely independent of the vehicle's lighting circuits. The # TM781117 doesn't work well with all vehicles. Your BrakeMaster will work, but you'll need a seat adapter, part # RM-88287 and a # RM-751449 stoplight switch kit, which is compatible with vehicles with non-adjustable pedals only. Since your GC has a combined taillight system,...
    view full answer...

  • TrailerMate 781118 Backfeeding Troubleshooting for a 2014 Jeep Grand Cherokee
  • I spoke to my contact at Trailermate and he informed me that there are diodes in the TrailerMate Harness part # TM781117 that prevent the RV from back feeding onto the tow vehicle wiring, but there aren't diodes in the kit to prevent the opposite direction of backfeeding. I know this isn't exactly the solution you are looking for, but he recommended you install diodes into the wiring at the 4-way like part # RM-790.
    view full answer...

  • Tow Bar Wiring Recommendation for a 2013 Jeep Grand Cherokee Being Flat Towed
  • The SMI Stay-IN-Play DUO Supplemental Braking System # SM99251 that you referenced is not designed to activate the stop/turn signals of a vehicle like your 2013 Jeep Grand Cherokee. It's sole purpose is to act as supplemental braking for a vehicle being flat-towed. For a lighting solution that would activate your stop lights and turn signals in conjunction with your tow vehicle you would want the TrailerMate Custom Tail Light Wiring Kit for Towed Vehicles # TM781117. This will install...
    view full answer...

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Info for this part was:

Photos by:
Theodore B
Written by:
Lindsey S
Expert Research:
Michael H
Expert Research:
Jameson C
Updated by:
Sarah W

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