Community Forums

Glen and Sal · 08-09-2020, 11:34 AM

We recently purchased a 2018 Jeep Cherokee Latitude 4X4 to tow behind our motorhome. It was already set up for towing with Roadmaster base plate, braking system and has the wiring harness installed for the power steering. I have been able to find information on the use of everything except the wiring harness. I've found lots info about the necessity of having the harness and how to installing it. What I can't find is the proper sequence of steps to engage the system. I found a procedure for a 2016 model that states to turn the vehicle off and wait for the bus to sleep. Then put the toggle switch in the tow position and then insert the 10a fuse. It goes on to say that if the ignition is turned to ACC or RUN it will cause system faults. If I do this procedure without turning on the vehicle, nothing happens and the steering wheel is hard to turn. If I start the car then turn it off the wheel turns easily as if the car is running, but I do get the faults. Is this the right procedure, or am I doing something wrong.

BobGed · 08-09-2020, 01:31 PM

The attached instructions are what I use for my 2014 Cherokee. They are a bit more detailed than your post so you already may be following the correct procedure, but it wouldn't hurt to double check.

I installed a switch in the cabin so I don't have to open the hood, but the sequence is the same.

Are you opening the car door between flipping the console switch and inserting the fuse under the hood? If so that can cause problems as the dash needs to remain dark through the entire procedure.

Glen and Sal · 08-09-2020, 02:01 PM

Thanks Bob.

I just tried your procedure. Leaving the door open the whole time so the dash stays dark. Switch to tow then insert fuse under the hood. Seems to be no change. Steering wheel is still "locked". I am not going through the whole procedure with the transfer case, just activating the EPS. I wouldn't think I would need to shift the transfer case to neutral to activate the EPS

BobGed · 08-09-2020, 02:05 PM

Quote:

Originally Posted by Glen and Sal

Thanks Bob.

I just tried your procedure. Leaving the door open the whole time so the dash stays dark. Switch to tow then insert fuse under the hood. Seems to be no change. Steering wheel is still "locked". I am not going through the whole procedure with the transfer case, just activating the EPS. I wouldn't think I would need to shift the transfer case to neutral to activate the EPS

No you wouldn't need to shift the transfer case.

Are you sure you're using a good fuse? If so try following the wire to the fuse block and make sure there is a good connection there.

Glen and Sal · 08-09-2020, 02:32 PM

The fuse is good, and there is power to the fuse. The EPS does activate if I start the car after doing the procedure and then shut it off. Steering wheel then turns freely.

Glen and Sal · 08-09-2020, 02:37 PM

The object is to get the steering wheel to turn freely correct? Could my required procedure be different from yours for the 2014 model?

BobGed · 08-09-2020, 02:51 PM

Quote:

Originally Posted by Glen and Sal

The fuse is good, and there is power to the fuse. The EPS does activate if I start the car after doing the procedure and then shut it off. Steering wheel then turns freely.

Whenever the EPS is activated by inserting the fuse and then deactivated by removing the fuse the steering wheel will continue to move freely for a period of time. Just what that time is I don't know as I've never tested it. I have read posts where it has remained active for anywhere from 10 to 15 minutes.

So when you say your wheel turns freely, have you by chance timed how long, or do you know it's indefinite?

One final question and then I've got nothing. What is the voltage of your battery with everything turned off?

Glen and Sal · 08-09-2020, 02:57 PM

I'll go check.

Glen and Sal · 08-09-2020, 03:28 PM

I activated the EPS by powering up the Jeep then shutting off. The wheel continued to turn freely. Went back 20 minutes later, and the wheel was "locked" up. Battery voltage was 12.4 volts when I started, 12.1 volts 20 minutes latter.

Bikinjim · 08-09-2020, 04:19 PM

Something is definitely wrong. The steering should immediately activate when you insert the fuse and stay active for about 10 minutes after you pull the fuse (or you turn on the ignition on and then turn it off), at least that’s how my previous 2015 Trailhawk worked. There may be a bad ground, a bad relay in the harness, a bad connection somewhere, or the wrong wire was cut and the harness spliced in when the harness was originally installed. I installed the harness myself on my car and getting the right colored wire took me a bit of examining to make sure I got the right pin and wire. I would first verify the harness is grounded good and then I would recommend following the installation directions and verify each step was correctly executed. By the way the switch in the console is only there to isolate the car’s CAN bus from the electronic steering so the malfunction indicator light won’t illuminate and codes won’t be set when the steering is activated by inserting the fuse when the ignition is off. It has no bearing whether the steering is energized or not.

The installation instructions are linked below. You want to verify the underhood steps, 35 and on.

https://community.fmca.com/applicati...nt.php?id=4344

Glen and Sal · 08-09-2020, 05:22 PM

Thanks Jim

Sounds like I do have a problem. I have talked to the previous owner of the Jeep and they never had a problem towing it. We have done one trip with it, about 300 miles one way and then back. We had no problems going. Loved the setup vs using the dolly (with a different car). On the way back we experienced the wobble 3 different times, so I don't really trust it now. I can check for a loose wire, but if it's a bad relay how would I check that. Can a Jeep dealer do a diagnose check on it to determent the problem?

Bikinjim · 08-09-2020, 08:09 PM

Glen, I towed mine for about 35k miles without a wobble including over some really bad roads in Alaska. Then we got our first low speed wobble on a bad road in Newfoundland and shortly thereafter a bad high speed wobble in Alabama before I could get the harness (backordered) and install it. My experience was once it starts it happens pretty frequently thereafter. But the harness did stop my wobbles after installing it. I am not sure how to troubleshoot hardware issues in the harness itself, but I have read a lot of owner experiences where the dealer did not correctly install it and the owners continued to experience wobbles because it wasn’t working. I personally would first verify 12v past the fuse (you basically said you did that already), and that it’s well grounded. After that you need to verify it was installed correctly (take to a dealer or go through the steps yourself per the instructions). It’s really just connecting +12v and ground and splicing in the the harness with solid connections to the proper wire under the PDC tray. The only trouble I had getting to the wire to splice in was in removing the tray, you just need to keep turning the retaining screws until the tray just lifts out, no prying needed. What’s left would be a defect in the harness itself and you may just want to go to a dealer at that point. Wish I could offer more help but you need to get it working before you have more wobbles and damage the car.

Glen and Sal · 08-09-2020, 08:35 PM

Thanks again Jim. I think I will try to check for a loose wire. Other than that I think I'll see if my dealer can check it out. We are planning a trip in a few days. Looks like I'll be pulling the old tow dolly out for this trip. I was hoping I was done with that. Just glad I didn't sell in when we first bought the Jeep.