We had a trip to a ORV parc last weekend. On one steep rocky and muddy climb I noticed some strange things with my JKU.
I crawled or drove up that climb until to many rocks and muddy surface was there. First all 4 wheels ( Rubicon with engaged locks) spun.
But suddenly I lost drive, the revs went up and I roleld back. So I hit the brake and gave it another try. Same thing. went up to a certain point all 4 wheels spun for a second and suddenly I the revs went up and I rolled back.
Did it 3-4 times to check and see what happens.
After this I rolled back a bit further put out 4L and tried to get in 4H. But didn´t manage it because I was in the middle of this steep rocky terrain and on the brake.
So I put in 4L again.......
and gave it another try. This time everything was ok. Spun the wheels for quite some time and nver lost the drive.

So it seems maybe 4L wasn´t in correctly. But I was driving around with 4 L for at least a couple of minutes without any problems and the shifter was also in the right position.

So, normal ? 4L not correctly engaged ?
Or a problem ?
Was a 9 month old JKUR

 

Did you turn off the ESP? If not i think the CPU will defuel slip clutch (not sure exactly what) to try to prevent a skid. In 4L I think it turns off ESP on its own. I could be wrong, Kind of a newb myself.

 

4H doesn´t turn off ESP
4L does turn it off. At least this light in the dashboard says it....
But I didn´t turn ESP off manually or with starting the car again a couple off times the manual off was "disabled"

But that´s a point to check anyway.

 

Seems like it slipped out of gear to me. Check the tranny fluid level to make sure it's not low. I doubt it was ESP related issue, because it gets turned off in 4Lo.

 

Sounds like 4lo wasn't fully engaged, mine has done that before.

 

You can upgrade to the cable shift that advance adapters offers which is a much more heavy duty setup than the OEM style with plastic clips/bushings/etc.