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Rubicon Transfer Case Falling Out of 4LO

11556 Views 20 Replies 8 Participants Last post by  christensent
2014 Automatic. Stock 4:1 transfer case with front and rear Tom Wood drive shafts with 1310 yokes.

This started about a month ago. Shortly after a big 4LO wheel speed hill climb (probably a coincidence), a few minutes later I was stopped and hit the gas in drive and it just revved for a few seconds then lurched into gear and went. A few seconds later I lost power again and it sat a few seconds then went. I had never once experienced this in drive (only time I've experienced similar symptoms is when switching from drive to reverse in 4LO, but that's a well documented and known software bug in the JK - but it feels exactly the same).

Next wheeling trip it just happened once, brief loss of power mid-way through a brief use of throttle.

Next two days on the trail, never had any problems all day.

Then today I had major issues. Dozens of times I'd be driving along and just suddenly lose all connection to the axles (both front and rear). Revs for a few seconds then gets going again with a lurch but no grinding gear noises. At one point it was oscillating between being in and out of gear twice a second for about 5 seconds. The computer at least sometimes knows that it's falling out of gear because the lockers will disengage and the 4WD light turns off (same things happen if you switch the case into neutral). There's no way to reproduce this issue and it happens in all conditions. Low-throttle "high" speed (10-15MPH in 4lo of course), or down hill engine braking (terrifying to lose that on a steep hill, almost wrecked the Jeep), or big hill climbs, or starting from a stop. But I can also do all those activities all day and have it never happen some days.

At no point does the lever actually move. It always stays in 4LO. Yes I know how to shift into 4LO and the lever shifts in exactly the same as it always has. I can feel the gears meshing if I'm moving very slow and go into gear and it feels good and normal. Pushing the lever towards neutral while engaged doesn't make it fall out so it doesn't seem likely to be a loose or poorly adjusted shift lever.

Could this actually just be an electrical issue? At one point today I was stopped after the issue happened and the 4WD light was just flickering for a few seconds. Does the transmission go out of gear if it thinks the transfer case is in neutral? Since there's no gear noise when it re-engages, I'm skeptical that the transfer case is actually going out of gear at all. It feels like the automatic transmission going into neutral and coming back. But this is my daily driver and this never happens in 2HI (I don't drive in 4HI enough to even know but I've never experienced it - I'm quite confident this is a 4LO issue).

Checked out the transfer case today and noticed that the front output shaft is leaking and the case is all oily in the front. I'll need to fix that, but I pulled the fill plug and oil poured out (factory over-fill) and was a good clean red color, so I seriously doubt the leaking output shaft is at all related since there's plenty of oil in there.

Anyone experience something like this? Any ideas? I don't have much knowledge in drive train diagnostics so not sure quite where to approach this. It can't be reproduced so I can't really take it into a shop and get help even if I wanted to (and no chance on dealer drive train warranty without reproducing it). Never seen this sort of issue discussed on forums.
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Since this post was brought up again, the problem was the transfer case position sensor, which is a little plunger sensor that detects where the lever is to tell the computer what tcase gear it should expect. I replaced it with an aftermarket replacement part, and it still did not work (actually was even worse). I then measured the resistance in each mode, put resistors on a 3-way switch, and I just flip the switch when I change between hi and lo, and never had a problem since.
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