Help?! 2020 JLU Fishtailed and Rolled From Potential Clutch and ABS System Failure

[JDJeep85]

Final Update: Thanks again for all the thoughtful suggestions and support friends. I was able to pull some codes from the vehicle post-incident that indicate potential clutch failure and electronic failure with the ABS system. I'm not a tech at all, just merely looking up the codes that showed up. I'm confident it will get sorted out eventually, and very happy to be uninjured. Thanks again and stay safe everyone

Hey folks,

I bought my JLU Willy's in the summer of last year. I've started taking my Jeep up to my local mountain for snowboarding days. I used to live in upstate NY and I am used to variable road conditions. 3 weeks ago when I was using the 4WD system (in snow) it made an odd noise and the check engine light came on. It also seemed like it would not shift into higher gears. It showed a "Service Trans" in the console errors. Took it into the dealership and they returned it to me the next morning. The notes in the invoice said that per Chrysler protocol, they just cleared the codes and gave it back to me after test driving it and not seeing any check engine lights come back on. Told me if it happened again, then they would consider looking at fixes.

Yesterday I was driving the same drive back up to the mountain, the roads had a pretty mild amount of snow/slush mix so I decided to turn on my 4WD High. The second I shifted the transfer case it felt like my wheels locked up and the Jeep started to fishtail wildly. I tried to mange the movement but couldn't control it. The jeep bounced softly into the snow bank on the right shoulder and the my Willy's ROLLED onto the drivers side and I quickly climbed out. No glass broke, no airbags deployed, no injuries to me or anyone else (that's the good news).

The bad news is....WTF just happened?

My Questions:

1. Has anyone else had an experience like this with their transfer case/4WD system!? I am extremely confident that I operated it correctly and the conditions were quite drive-able, I had little Hondas passing me with no problems at all.

2. It surprised me that the Jeep rolled with so little force and given the direction of the force (being mostly to the front right corner). I know Jeeps can roll, but this seemed a little gratuitous. Does this seem "expected" to you all?

Thanks for any insight or help, taking it back to the dealer next week.

Also in the notes from the service before this happened were a bunch of codes (again this is what they just cleared before returning to me):

"the codes that i found in the system reads:
TCM P0721-00 Output Shaft Speed Sensor Circuit Performance-Stored
TCM P0607-00 ECU Internal Performance-Stored
PCM U0418 Implausible Data Received From Brake System Control
Module 1 Stored
ABS U0402-00 Implausible Data Received From TCM-Stored
DTCM U0402-00 Implausible Data Received From TCM-Stored"

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[The Last Cowboy]

Those codes are what recorded the crash event. When a diagnostic computer is hooked up it will show the exact speed that you were going 5 seconds before the event, your RPM, steering angle brake modulation, etc. I am a traffic accident investigator, so that's how I know what those codes are for.

Is this your first Jeep and first part time 4x4? I'm afraid that this is a hard lesson learned. Show us a picture of the snow bank and I can probably guess what caused you to roll. What PSI were you running in those tires? And, those are not good tires for snow and ice, unless you stud them which the sidewalls indicate that you can.

Sorry this happened. The good news is that no one was hurt and there is no crush on your Jeep and it can be fixed fairly easy.

 

[LDJD79]

Damn that sucks. We’re you able to drive it home after you got it flipped back over? I have had my 18’ JLUR throw a service 4 wheel drive system code when I shifted into 4WH going down a steep hill with loose rocks. After this happened it still showed me in 4WH but the front wheels weren’t pulling. I had to use my taser to clear the code before it started working correctly again.

Got to ask, you didn’t shift into 4WL did you?

 

[aldo98229]

Welcome to the forum.

Geez, sorry man. And you are not that far from me.

I agree with @The Last Cowboy that MT tires suck in snow. But that doesn’t explain why your wheels would lock.

I believe the reason you rolled is because your passenger-side tires climbed up the wall of snow.

Hope you get things resolved.

 

[JDJeep85]

Those codes are what recorded the crash event. When a diagnostic computer is hooked up it will show the exact speed that you were going 5 seconds before the event, your RPM, steering angle brake modulation, etc. I am a traffic accident investigator, so that's how I know what those codes are for.

Is this your first Jeep and first part time 4x4? I'm afraid that this is a hard lesson learned. Show us a picture of the snow bank and I can probably guess what caused you to roll. What PSI were you running in those tires? And, those are not good tires for snow and ice, unless you stud them which the sidewalls indicate that you can.

Sorry this happened. The good news is that no one was hurt and there is no crush on your Jeep and it can be fixed fairly easy.

These codes were from 3 weeks before this incident occurred, when I reported odd behavior with the transfer case to the dealership/shop.

No this is not my first vehicle with part time 4X4, it is my first Jeep however. But I don't really understand what lesson I should be learning from this. I assume that shifting the transfer case into 4WD High at a normal/slow speed going straight shouldn't cause the wheels to lock up...?

Also I realize these are not studded tires, but they are described by Jeep and the manufacturer like this and I also don't think the tires seemed to be related to the lock-up...the conditions were quite mild with some wetness.

"Engineered to perform in the most demanding off-road conditions, the Firestone Destination M/T2 tire features mud and stone rejectors to keep the tire’s tread clear of debris for increased traction, and an advanced sidewall construction offers resistance to chips and tears. Additionally, the Firestone Destination M/T2 tire has biting edges for better grip on slick, wet surfaces and in snowy conditions."​

 

[JDJeep85]

Damn that sucks. We’re you able to drive it home after you got it flipped back over? I have had my 18’ JLUR throw a service 4 wheel drive system code when I shifted into 4WH going down a steep hill with loose rocks. After this happened it still showed me in 4WH but the front wheels weren’t pulling. I had to use my taser to clear the code before it started working correctly again.

Got to ask, you didn’t shift into 4WL did you?

Ha no I did not shift into 4WL Yes I was able to drive it home (almost a 2 hour drive O_o)! It went into the AutoPark safety feature after getting it back up, which the tow driver couldn't figure out how to clear. I had to cycle it on and off and through park/drive a couple of times before it wanted to move.

I haven't pulled any codes from it yet, after this incident, but I will before sending it back to the dealer just to check it out myself, though I am not tech and don't really have any deep knowledge on what they all could possibly mean.

 

[BlackGenesis]

M/T tires are not good in snow compared to A/T.
Sounds like rear lock up fully to cause this. Is your transfer case shifter dificult to move from 2H to 4H?

 

[JDJeep85]

M/T tires are not good in snow compared to A/T.
Sounds like rear lock up fully to cause this. Is your transfer case shifter dificult to move from 2H to 4H?

Yes it's actually very hard to pull down/shift, so much so when I first used it I thought something was wrong with it.

 

[Left Field]

Looks like I-90? If so that's a section of winter highway I drive a lot, in fwd, rwd and 4wd and with many types of tires. Maybe the MTs aren't the perfect tire, but with reasonable driving the the tires, especially with low mileage / sharp tread, should not be the problem.

The second I shifted the transfer case it felt like my wheels locked up and the Jeep started to fishtail wildly.

I've had some weird driveline / handling events before, but always able to trace to a failure or other cause. The event from a few weeks ago sounds like something binding up , or some transmission problem. Hopefully some info comes to light. Some brainstorming:

1) Any chance that FCA messed up the front / rear diff gearing?
That would break everything loose when you hit 4Hi. Easy to check by driving a short distance in a straight line on dry pavement while in 4H. Binding should be minimal.

2) Maybe a problem with traction control (or other active braking systems)? If one of the active braking functions incorrectly thought one or more wheels were slipping it would start applying brakes to those wheels - in this case possibly inappropriately and causing loss of traction.

3) Transmission went into an incorrect gear (or gears) and caused driveline drag or even lock-up, resulting in wheel skid. Rear skidding , esp with limited slip can result in severe fishtailing.

The dealer is likely going to drag their feet on investigation and may even clear codes again. There are some clever folks on here, hopefully with a bunch of good suggestions.

 

[Fsttanks]

These codes were from 3 weeks before this incident occurred, when I reported odd behavior with the transfer case to the dealership/shop.

No this is not my first vehicle with part time 4X4, it is my first Jeep however. But I don't really understand what lesson I should be learning from this. I assume that shifting the transfer case into 4WD High at a normal/slow speed going straight shouldn't cause the wheels to lock up...?

Also I realize these are not studded tires, but they are described by Jeep and the manufacturer like this and I also don't think the tires seemed to be related to the lock-up...the conditions were quite mild with some wetness.

"Engineered to perform in the most demanding off-road conditions, the Firestone Destination M/T2 tire features mud and stone rejectors to keep the tire’s tread clear of debris for increased traction, and an advanced sidewall construction offers resistance to chips and tears. Additionally, the Firestone Destination M/T2 tire has biting edges for better grip on slick, wet surfaces and in snowy conditions."​

I believe you about the codes. Welcome to the glitchy JL electrical world. My electrical systems is totally unreliable (2020 JLUR 5k miles ). I have had a number of on road dangerous power losses and system issues while driving, all would have been worst had I been driving were you were.

Jeep is of no help with electrical issues and doesn’t know how to fix them. I bet your computer glitched as you were switching from 4HI and caused other systems to act incorrectly.

Glade you are safe and walked away only shaken and not physically hurt.

 

[Suffolklou]

WOW that sucks. I will be watching this to see if you figure out what happened

 

[McGilli]

At least you could drive it away

Wow...

Could you post a photo of the drivers side of the Jeep now?

 

[Joe98]

Yes it's actually very hard to pull down/shift, so much so when I first used it I thought something was wrong with it.

Mine moves smoothly implying yes there is something wrong with yours.

And when moving into or out of 4WL, that too is smooth so long as I follow the procedure.

 

[JDJeep85]

Looks like I-90? If so that's a section of winter highway I drive a lot, in fwd, rwd and 4wd and with many types of tires. Maybe the MTs aren't the perfect tire, but with reasonable driving the the tires, especially with low mileage / sharp tread, should not be the problem.



I've had some weird driveline / handling events before, but always able to trace to a failure or other cause. The event from a few weeks ago sounds like something binding up , or some transmission problem. Hopefully some info comes to light. Some brainstorming:

1) Any chance that FCA messed up the front / rear diff gearing?
That would break everything loose when you hit 4Hi. Easy to check by driving a short distance in a straight line on dry pavement while in 4H. Binding should be minimal.

2) Maybe a problem with traction control (or other active braking systems)? If one of the active braking functions incorrectly thought one or more wheels were slipping it would start applying brakes to those wheels - in this case possibly inappropriately and causing loss of traction.

3) Transmission went into an incorrect gear (or gears) and caused driveline drag or even lock-up, resulting in wheel skid. Rear skidding , esp with limited slip can result in severe fishtailing.

The dealer is likely going to drag their feet on investigation and may even clear codes again. There are some clever folks on here, hopefully with a bunch of good suggestions.

Thanks for the suggestions/ideas, I am going to at least try to pull the codes so I have a copy before sending it back to them. Another friend recommended asking for a Factory tech review instead of just a service tech, which might be a nice idea.

 

[JDJeep85]

Mine moves smoothly implying yes there is something wrong with yours.

And when moving into or out of 4WL, that too is smooth so long as I follow the procedure.

Interesting, mine is very stiff.

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