Join Date: Aug 2016
Location: Fort Wayne, Indiana
I believe, could be wrong, that the overheating causing the 4wd unavailable message is the clutch pack in the rear diff unit that provides the necessary slip for am all wheel drive scenario on hard ground. When on slippery ground the constantly slipping front or rear wheels is allowingor promoting slippage in the clutches and therfore generating heat. It would be nice since the computers obviously monitors the temp to be able to display it to know in advance if overheating is likely.
If this is the case then I am surprised in snow as it does not have a shield. Though possibly the front shields are lower than the diff so it's always sitting above the snow and not dragging through it.
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You are 100% correct. When the rear drive shaft engages, the front clutches in the wet pack begin to spin which heats up the goo inside and engages the rear clutches, which then spin the rear differential, and thus the rear wheels. Depending on how much tire slippage is occurring, front to back, side to side, makes this clutch pack work harder to stay engaged. Once the clutch pack reaches a certain temperature, it disengages and thus the message. When I finally found out how this system works, I was highly disappointed. I can't believe that Jeep would use one of these. In a Jeep, it needs to be a mechanical connection; not a wet one. Jeep is known for its off road prowness; this is why Jeep sells more SUVs then anyone else.
A few years back, Car and Driver did a test of a bunch of 3 row SUVs. They ended up at the sand dunes of Western Michigan. They tested a Durango (mechanical connection) against a bunch of what were basically FWD (Explorer, Honda Pilot, one of the GMs; I don't remember all of them). All off these had a wet pack clutch unit which would send power to the rear wheels. All of them overheated, so 4WD was not available and the Durango had to pull them out as each one of them got stuck in the sand. Sad.
2016 Cherokee Trailhawk: Mango Tango Pearl Coat over Black.
OPTIONS: Every Available Factory Option/Package Except Remote CD Player.
MODS: Whispbars; Mopar Cargo Cover; Mopar Cargo Mat; Mopar/KICKER 9 Speaker Upgrade; KICKER Sub and Amp; Ziebart Undercoating; aFe CAI.
FUTURE MODS: Remote CD Player; Mopar Rock Rails; Rear Fog Lights.
Last edited by dhh3; 03-15-2017 at 11:30 AM.