[ygdude]

bought our 2014 Cherokee new in 2014. I installed a MOPAR factory hitch (bumper beam type), new bumper cover and MOPAR wire harness kit.

Things have worked well since. A while back i had some issues with the trailer wiring and wasn't getting any lights on the tailer. I disconnected the batter on the Cherokee for a bit to reset things and the trailer lites started working again.

last fall i wasn't getting lights again so i was poking around with my multi-meter to see if i had voltage and had a small spark and then nothing at all. ALL the Jeep lights work fine. no issues.

I presume i may have shorted something and blew a fuse.

SInce this was not put on at the factory none of the fuses in the fuse box for normal trailer towing accessories work.

so, does anyone know where the problem might be staring with what fuse should i check?
I've attached a couple sections of the installation manual that came with the MOPAR wire harness. Specifically looking at the wire in views 25 and 26 where you plug the wireharness wire into the plug under the drivers knee bolster. Nothing obvious in the owners manual or fuse box that would power this.

 

[valiant67]

Most likely the hitch requires the physical hitch installation plus the wiring. Then the wiring is enabled through the computer so the new accessory gets power.
This was how it was done on my 2014 Durango. I know there Cherokee is different, but I suspect the same process is involved.

 

[AllanC]

. . . I disconnected the batter on the Cherokee for a bit to reset things and the trailer lites started working again. . . .

last fall i wasn't getting lights again so i was poking around with my multi-meter to see if i had voltage and had a small spark and then nothing at all. ALL the Jeep lights work fine. no issues.

I presume i may have shorted something and blew a fuse. . . .

Did you install the wiring harness kit yourself or did you pay another party to install? There should be a power wire for the wiring harness that connects to the positive terminal at the fuse box / TIPM. Also I would expect there to be an inline fuse holder for that power wire. I would check and see if present that the fuse is good.

I found this Y T video that shows installation of the MOPAR trailer tow wiring harness on 2014 Jeep Cherokee.

At time interval 14:20 the presenter attaches the trailer tow wiring module. Find that module and check for 12 volt power. I would expect a red wire from the engine compartment to provide constant power to the module.

At time interval 19:25 connection of power wire to fuse box terminal. Time interval 19:40 the presenter shows a connector which could be the inline fuse holder.

If you find power to the lighting module but no operation your short circuit might have damaged and caused the lighting module to fail.

 

[ygdude]

Did you install the wiring harness kit yourself or did you pay another party to install? There should be a power wire for the wiring harness that connects to the positive terminal at the fuse box / TIPM. Also I would expect there to be an inline fuse holder for that power wire. I would check and see if present that the fuse is good.

I found this Y T video that shows installation of the MOPAR trailer tow wiring harness on 2014 Jeep Cherokee.

At time interval 14:20 the presenter attaches the trailer tow wiring module. Find that module and check for 12 volt power. I would expect a red wire from the engine compartment to provide constant power to the module.

At time interval 19:25 connection of power wire to fuse box terminal. Time interval 19:40 the presenter shows a connector which could be the inline fuse holder.

If you find power to the lighting module but no operation your short circuit might have damaged and caused the lighting module to fail.

thanks for the video,
My set up did not have a wire to the battery. only 1 wire that goes to the plug under the steering wheel in BOX #29 in the instructions. Maybe the one in this video is newer car/harness kit or a different set up for trailhawks??? anyway. it had worked fine for 6 years.

I haven't gotten around to pulling the interior out (huge pain in a##) to check the small box and wires in the back (14minute area in video). I cannot remember if there was a fuse in there or not. It seemed like there were 2 things. the small box and maybe another small item inline in one of the wires. > if so, then possibly an inline fuse. Lousy place to put one but possible.
**so anyway. that is part of the reason for my question and post to see if anyone knew anything about how the system is powered and/or which fuse under the hood to inspect before taking the Cherokee apart.

Thanks.

 

[AllanC]

. . . My set up did not have a wire to the battery. only 1 wire that goes to the plug under the steering wheel in BOX #29 in the instructions. Maybe the one in this video is newer car/harness kit or a different set up for trailhawks??? anyway. it had worked fine for 6 years. . . .

I am thinking that is a single cable but contains 2 wires; power and ground. I cannot imagine today engineering a system with only 1 wire / conductor.

Does your application have a single cable to the GREY connector and another single cable to the BLUE connector?



The challenge is to determine what function the terminals behind the GREY connector and BLUE connector provide. It is either ground circuit and power for left turn / stop lamp, right turn / stop lamp, and tail lamp. Or it is an extension of the vehicle network and 2 wires carry commands to a rear lighting module which interprets commands and activates turn signals and brake lamp.

 

[ygdude]

I am thinking that is a single cable but contains 2 wires; power and ground. I cannot imagine today engineering a system with only 1 wire / conductor.

Does your application have a single cable to the GREY connector and another single cable to the BLUE connector?

View attachment 79113

The challenge is to determine what function the terminals behind the GREY connector and BLUE connector provide. It is either ground circuit and power for left turn / stop lamp, right turn / stop lamp, and tail lamp. Or it is an extension of the vehicle network and 2 wires carry commands to a rear lighting module which interprets commands and activates turn signals and brake lamp.

>There is only 1 wire to the front. As shown in the #27 box of the instructions i attached in the original post. The Grey connector only had 1 wire in it and Box #27 shows how to add the single wire from the MOPAR trailer harness to the Grey connector (now it has 2 wires).

Good thought on that single wire being power? or signal?. THe harness taps into both of the rear tail/turn signal wires inside the corners behind the taillights (like the video you attached for the TrailHawk) so in theory they would get power from those (??). There is also small box like the TH video that attaches in the rear drivers interior.

here is a view of the wire harness itself.

The RED circles go to each taillight. THe green goes to the little black box in the rear. The Purple plugs into the back of the bumper plug and the Blue goes to the front. Note: the little square thing on the front wire is not a plug. Not sure what it is but it only gets zipp-tied to the underside of the dash. I was wondering if there might be an inline fuse in that but haven't taken dash appart to look. (its pretty cold out this week).

Thanks!!

 

[AllanC]

. . . Good thought on that single wire being power? or signal?. THe harness taps into both of the rear tail/turn signal wires inside the corners behind the taillights (like the video you attached for the TrailHawk) so in theory they would get power from those (??). There is also small box like the TH video that attaches in the rear drivers interior. . . .

Good job for presenting the wiring diagram again and identifying the components. Since there is a means to tap and splice into the left rear and right rear taillight assemblies there is no need to get power for the left rear and right rear trailer lights from the dash area or engine compartment. So you are correct in that assessment.

. . . The RED circles go to each taillight. THe green goes to the little black box in the rear. The Purple plugs into the back of the bumper plug and the Blue goes to the front. Note: the little square thing on the front wire is not a plug. Not sure what it is but it only gets zipp-tied to the underside of the dash. I was wondering if there might be an inline fuse in that but haven't taken dash appart to look. (its pretty cold out this week). . . .

I agree that the small holder zip tied under the dash could very well be a fuse holder. When you have the opportunity take a look. You may have found a simple fix. If there is no failed fuse then the next place to look is that black box / lighting module.

I did some research and found an explanation for the rear lamp module. From MOPAR description of the wiring harness. Tapping into the LF rear and RR stop lamp circuits would allow a means to provide signal power to electric trailer brakes. The 7 pin weatherproof connector has a port for this feature.

The Mopar Trailer Tow Wiring Harness Kit, item #82213938AF, includes 7- and 4-way trailer connectors and a lamp module that uses inputs from the brake lamp and turn signal lamp. Note that in most jurisdictions it is illegal to tow a trailer that does not have operating lights; stay legal with this Mopar part.

So I am thinking under the bumper you have a round weatherproof electrical connector with 7 pins??? And there is a flat weatherproof connector with 4 pins???

 

[ygdude]

Yes, Item F in the wire harness picture is the plug that installs in the hitch/bumper. It has the "old style" flat and the more modern round both.

I wonder if the black box is goofed up then the plug was shorted.

 

[AllanC]

. . . I wonder if the black box is goofed up then the plug was shorted. . . .

Time to do some testing / check out of circuits. Check holder wire tied under dash for a fuse. If found check to make sure it is good. Once that is verified move to the rear.

You have indicated that the rear lamps are working properly. So the left rear and right rear lamp assemblies have power. See attached diagram and check for power input to the lighting module supplied with the trailer tow adapter harness. If power into the lighting module but no power out then the module has failed. Conclusive proof.

I have included a schematic which should be the color wire coding convention used as an industry standard for the round 7 pin electrical connector. It will be different that the color coding Chrysler uses.