I have a 2014 V6 TH with 120k miles.
Can't say if your RDM is ok or not. Strange things happen when driving on ice.
The LAST thing you want your rear tires to do on ice is slip, the rear end can go out of control. It is best if the tires just sit there and do nothing.
Do you have 3 peak mountain snow flake snow tires on all 4 wheels? If not all bets are off. You need physical traction with the road surface for anything to work.
Seems the rear locker works ok. The computers have a mind of their own in order to provide traction.
Remove the right side RDM fill plug, look for excessive metal on the magnet, fine metal filings are ok.
Does your left rear axle seal weep or leak? If so add the correct gear oil to the right side to top it up.
I don't have any idea what a "stub shaft" is.
70k is low mileage, my guess is that everything is fine.
Have your Jeep dealer confirm all recalls are complete and applicable TSBs are done.
Have the Service Advisor print a VIP report and review it with you.
Let us know what you discover.

 

I have a 2014 V6 TH with 120k miles.
Can't say if your RDM is ok or not. Strange things happen when driving on ice.
The LAST thing you want your rear tires to do on ice is slip, the rear end can go out of control. It is best if the tires just sit there and do nothing.
Do you have 3 peak mountain snow flake snow tires on all 4 wheels? If not all bets are off. You need physical traction with the road surface for anything to work.
Seems the rear locker works ok. The computers have a mind of their own in order to provide traction.
Remove the right side RDM fill plug, look for excessive metal on the magnet, fine metal filings are ok.
Does your left rear axle seal weep or leak? If so add the correct gear oil to the right side to top it up.
I don't have any idea what a "stub shaft" is.
70k is low mileage, my guess is that everything is fine.
Have your Jeep dealer confirm all recalls are complete and applicable TSBs are done.
Have the Service Advisor print a VIP report and review it with you.
Let us know what you discover.

"Strange things happen when driving on ice."

No they don't. It's worked perfectly until this point. 4wd has been engaging as it should until today. It's not working. I can't move on snow/ice because the rear wheels are not engaging. 4 low/mode select has no bearing on its operation UNLESS the rear differential is locked. Only then does it apply power to the rear.

Attached is a parts breakdown of the RDM. The circled "output shafts" are also referred to as "stub shafts". If one of these are sheared, the RDM becomes useless in normal "open" differential mode.

"Do you have 3 peak mountain snow flake snow tires on all 4 wheels? If not all bets are off. You need physical traction with the road surface for anything to work. "

Huh? Mud terrains. Again, they all worked until today. Tires have no bearing on weather the drivetrain works or not. It worked yesterday and every day since 2014 until right now.

No leaks, I check the level every oil change and there's no damage. TSBs were done last year along with the PTU. PTU is not reporting any codes to the DTCM or TCU (I have a full Alfa OBD license). There are no codes present anywhere.

"The computers have a mind of their own in order to provide traction."

By removing the power to the rear wheels? Not likely, as its never happened before. EVER. I feel like you're just making excuses at this point and really just wasting time to up your post count for whatever reason.

I would try it in some loose gravel or something besides ice. Like @sanghill said, it's possible that the system is sensing too much slipping, and putting all the power to the front. Have you tried going through all the terrain modes in 4High and 4LOW??? That's what I would do. It's a pretty complex system...😎

Loose gravel, snow, ice... Low traction, same difference and wouldn't make a bit of difference because it worked literally yesterday and every day before that (aside from the PTU failure in 2021).

"it's possible that the system is sensing too much slipping, and putting all the power to the front."

It's NOT possible that its routing the power to the front only, as that's not how the system works or has ever worked to this day.

"Have you tried going through all the terrain modes in 4High and 4LOW???"

Have you tried reading the original post?

I really hate to sound offensive here, but these two posts alone have literally contributed nothing. This is why forums are dying.

 

I would try it in some loose gravel or something besides ice. Like @sanghill said, it's possible that the system is sensing too much slipping, and putting all the power to the front. Have you tried going through all the terrain modes in 4High and 4LOW??? That's what I would do. It's a pretty complex system...😎

 

OP understands the problem, which he has confirmed.
If you lift the Jeep by the frame is it possible turn the LR wheel to confirm if the stub shaft (part 10) is broken?
Somehow lock the internal parts in position and see if the LR wheel still turns.
I have the same year TH so I really want to understand what is happening, maybe it will help me prevent it from happening to my TH.

 

@ChaoticGorilla we are trying to help you since we are not in person with the Jeep we have to ask questions to try to narrow it down. If you have a full Alfaobd license you can use that software to run tests on the RDM and also override and attempt to engage it outside of 4wd low. It's quite possible something has failed though the RDM's typically fail in a fashion that either makes some noise or error code. Try using alfa to make sure there is no stored codes and the RDM passes all tests. As an example when my PTU was failing it failed testing when I tried to cycle the actuator motor.

As for what we were asking on tires. 3 peak snow rated tires do not have to be mud tires or winter tires. 3 peak severe snow rating is just a snow rating that good tires typically carry if they were designed for much snow/ice use. Standard all seasons can carry the rating and the 3 peak symbol if they pass the testing for it. Many people run 3 peak rated tires because they give you the benefit of a tire you can run year round even in moderate snow conditions and get good performance. Winter tires are still better in snow but you cannot run those year round. 3 peak is a happy medium.

 

Returning to contribute to the knowledge base, before I abandon this vehicle in its entirety.

I had the vehicle towed to a dealer for a diag, and they gave me the normal "PTU, RDM and DTCM all require replacement" with a grand total of $10,240. I declined the repair and towed the vehicle to my home. I removed the RDM and tore it down to inspect for a failed bearing or worse...

I drained the grease, which looked fine aside from several large shards of what appeared to be hardened steel. Upon disassembly, my suspicions were confirmed. #27 in the parts illustration pictured above is broken at the spline. This explains why the ABS was pulsing rear brakes (ELSD activation) with no power going to the rear while the fronts were slipping in 4 high. When in 4 low, I was able to get one rear wheel (left rear) to operate only when the locker was activated. If the locker was disengaged, no power was being applied to the rear wheels but the rear driveshaft was spinning.

Under further inspection I discovered the differential to have improper, shallow pinion depth causing undue wear to the top of the drive side of the ring gear. This also created excess gear lash in the amount of .018". I then found that the differential side-load was inadequate reading a total of .007" of axial play. As we know, there is no differential servicing information out there such as lash specifications or even parts breakdowns of the internals of this unit. The specifications I'm using are from experience, as most axles/transaxles/drive units have .005 -.012" of gear lash and .000" of differential axial play. This is normally shimmed out using differential bearing shims.

I must say. This is a poorly manufactured unit and the ring gear is so small that I question FCA's tow/capacity ratings of this vehicle. The inside of the case had casting sand stuck in pores, the seals were hastily installed, some crooked and/or slightly damaged (but not leaking).

My honest opinion, I'm going to put a used RDM in this thing and send it on its way before the next "$10k" repairs are required.

 

This is both tragic and informative. Especially since I have 2014 TH with factory tow.
One of the main reasons I got the tow package was so there would be sturdier parts.
I never tow anything, but was hoping for more reserve hill climbing capacity.
I go off road regularly and always use the rear locker. I really put a strain on the drivetrain.
In my experience axles rarely break unless the steel was not hardened correctly.
You might need to get a truck so you get the ground clearance and durability that you need.
SUVs in general seem to be rather fragile.
Let us know what you get for off road.
This is the other recent Post discussing a new RDM: 2014 Cherokee Rear Differential AD11
Check the used car parts company I referred to in Post #2.
Thanks for the education and insight. Merry Christmas.