Quick question we have a 2017 Rubicon Recon that only has 13k miles bought it with 6,900 miles and it had never been off-road til we bought it, under carriage looked like it rolled off the showroom floor but the last couple times when trail riding we put it in 4 low and try climbing a steep hill it has zero power and will not put it’s self up the hill. 4 high is fine with no issues, no issues in 2wd either. Tried it at home on some smaller hills and worked perfect. Has me stumped, anyone experienced this? No noise when shifting, shifts perfect. Has to be something simple I just can’t figure it out

 

I had a rear wheel speed sensor going bad and it would cut power in 4lo but be fine in 4h and 2wd prior to it actually throwing a code. New rear speed sensors was the cause and fix in my case.

 

Thanks a lot I will check it out

 

Could be the system does not realize you are in 4L. Does it presently disable ESC on the display when you switch to 4L. Should ring a chime and display a message. In this case if it does not then I would suspect the transfer case sensor switch. These things do break from lack of use as well. I run mine through all transfer case settings on a gravel road at leat once every two weeks for that very reason. My diffs lock instantly now as before they took their merry old time doing so.
Remember the saying - Use it or lose it?