Last updated on August 9th, 2020 at 09:17 pm
Project Difficulty: Medium-High (wiring & programming needed)
Time taken: 8 hours
Cost using the method in this writeup: $535.00
So I set out on what I thought was going to be a relatively straight forward tow hitch installation on my 2018 Jeep Grand Cherokee Limited 3.6L V6, but was shocked at the level of complexity and lack of resources to complete the job the right way. I finally figured it out, at the expense of my own wallet so I figured I'd do a quick writeup for those who are looking to do the same installation on a similar (or same) year Grand Cherokee. In this writeup, I'll go through the hitch that I used, wiring along with the programming software to enable everything on the computer.
My original plan was to tap into the tail light leads using a universal 7 pin/4 pin adapter and place it in the aftermarket hitch that I purchased that has a factory-look and built into the bumper. The hitch and bumper installation was simple enough but I decided to do this the proper way and integrate it into the existing wire harness of the car like the dealer would. I'm not saying you can't use the taillight leads to do this installation but I'm not sure it's going to get you what you need. Jeep has made this process a complete nightmare in my opinion, especially for those who don't have the built-in wiring.
Apparently mid 2018 and later models of the Grand Cherokee that don't have the tow package no longer have the wiring either which added to my frustration. And even the folks who do have the wiring built in on older models still have to program/enable the pins in the ECU which is a $185 trip to the dealer. Or at least my dealer. I've read of charges as low as $40. So let's get to it.
Tools & Parts List:
Apart from your standard tool set with sockets and such, here's a list of the products and some of the special tools I'd recommend, with links to the parts on Amazon:
Tow Hitch Installation
For the hitch installation, I chose a class IV hitch receiver that included the bumper bezel. You have two options for a hitch on the Jeep:
- OEM look – This is the hitch that I chose to use. It replaces the existing bumper support and the hitch itself goes directly through the bumper. It typically comes with a bezel. Using this type of hitch will add to the time of your project because you have to remove the rear bumper and cut the bezel manually. Here's the one I used.
- Under the bumper look – I personally don't like this look. The hitch sits below the entire bumper which would likely put it in a place that would require you to have to get a hitch raise too if you want your trailer to be level. This, to me, just looked cheaper.. and it is. It's cheaper to install, cheaper to buy and easier to install if you're doing it yourself. It simply mounts to the bottom of the existing frame so you don't need to pull the bumper off and replace the bumper support bar. You can find an example of this type of hitch here.
To install the OEM-style hitch you'll need to do a few things:
- Partially remove the rear fenderwell trim pieces. This is to access the screws to the bumper. There are a few push-style clips along with plastic rivets that you'll need to drill out to get the trim piece off.
- Remove the bumper. There are screws on the inner side of the hatch, behind the fenderwell and two underneath on the bottom side of the bumper. Once this is removed, you can replace the bumper support frame piece.
- Remove the bumper support by removing the 6 large bolts that hold it in.
- Cut out out the rectangular hole in the bumper to make room for the new hitch and the bumper. If you purchase the hitch that I did here, you can actually use the template that's already pre-built into the back of the bumper. This was a surprise for me. There's an actual light imprinted template for where the factory would cut out the OEM bumper to make room for the factory bezel. It just so happened to work perfectly for this bezel too. Sorry in advance but I didn't get pictures of this or the process to cut it out of the bumper. I just used a combination of a sharp drywall knife and a dremel to do it and it came out perfect.
- Install the new hitch where the old bumper support was.
- Reinstall the bumper and the fenderwell trim pieces.
Here's a few photos to help explain.
Wiring the Mopar Harness
Wiring the Mopar from the rear to the front of the vehicle was straight forward. It comes with instructions, but I also uploaded them here for you to look at them. The kit comes with the wire harness, zip ties and a new ‘PDC' box that you'll replace in the engine bay. Here's the instructions.
The instructions are pretty thorough in terms of where to wire it and the different harness clips to tap into. It was pretty helpful. I'll let you review it instead of me duplicating the instructions, however, there are a couple things to call out specifically that I found in terms of discrepancies between the instructions and the wires in my vehicle.
- In step 29, the C5 harness visual is NOT correct. The pins 24, 23 and 22 are not located on that side of the harness when you're looking at it from the wire side. Rather, they're on the other side. Use the pin numbers that are on the harness to place your wires and NOT the visual in the instructions.
- There is a WH/DG (white and green striped) wire in the harness, but there is not a WH/GN wire. Rather, there's a solid white at least in the harness I got. This doesn't necessarily matter though. As long as you map the same wires labeled as WH/DG or WH/BN, etc that's in step 29 with the same labeled wires in step 44 and 45 you'll be fine. For example, I used the solid white wire that was in my harness as the “WH/DG” in pin 22 on the step 29, and then wired it to the location that the “WH/DG” was in step 44.
- If there are pins that exist in the harness where the wire is supposed to go, take a picture of the harness as it is, then remove and replace them. Take a picture so that if you mess up, you know where to put them back. I took pictures of everything before.
Apart from those callouts it worked great. I wouldn't be too intimidated by the instructions either, once you have each of the harness clips in your hand, they have pin #s labeled (in fine print but it's there).
Programming/Enabling the Tow Wiring on Your Grand Cherokee
This is honestly where I felt Jeep went overboard with the amount of control that they wanted with these cars. Not only do you have to wire the harness for ‘mid 2018 and newer' Grand Cherokees (with the slight mistakes in the directions), you have to actually connect to the car with software and enable the pins to have power. And even IF your Jeep was prewired, if you don't have a tow hitch installed or the 4 or 7 pin connector you'll likely need to program yours as well.
Worry not though. I found a way to do this with a cheap alternative instead of paying $150 – $200 bucks at the dealer. At the time of this article, I searched for HOURS to figure out how to do this and I didn't find any instructions. You can do it in your garage with your own laptop, and for about $65 bucks.
The program is called Appcar DiagFCA. Their website: https://appcar-diagfca.com/en/. For $49 dollars you'll get access to the program, but it's only for Windows devices. I actually have a Mac and used a program called Parallels to run Windows 10 on my mac computer at the same time and it worked fine for me (that's another article in its own if you're not familiar with virtual machines).
You'll also need an OBDII to USB device. It needs to be ELM327 compatible, the one that I purchased is here. At the time it was $18 bucks. Once you have the software, the OBDII device and your wiring is installed in your Jeep, you're ready to start to program. Plug your OBDII chord into the vehicle, turn your key (or push your button) till the car is in accessory mode, then plug your USB into your computer and let the drivers install. On my computer it registered immediately and installed the drivers automatically.
Once your drivers are installed, open up your Appcar DiagFCA program and follow the steps below. Scroll through the images to see the steps in the gallery below:
Boom! You're done. I would unhook the battery for a couple minutes to reset the system, then begin checking your 7 pin harness in the rear to make sure that everything is ok. The signals are labeled on the 7 pin cover to make it easy for you to hook your volt meter. Note, I've heard that the left and right turn signal may become mixed up for some reason. If, for any reason one or two of your pins are mixed up you can always just unpin the harness at the hitch and move them around to make them match the correct setup.
Update 6/23 – Per some requests, I've uploaded all of the original photos of the harnesses that I took in case I accidentally needed to revert or pinned a wire incorrectly and needed to start fresh. See below.