392 Transfer case failing me

[1996cc]

Stock 392 with stock Tcase. Running 4.88’s & 37”s with tazer. Bought with 5,000 miles on it, 11,000 now. I’ve been driving in 2wd mode since I bought it, and previous owner likely was too, since it was that way on the dealer’s lot. Communicated with Scott Blum & Joe from Zauto on FB and they have both assured me that 2wd mode isn’t hurting anything since it’s the exact same case used in the 4xe & Mojave that have 2wd modes.

Enough history, yesterday in the dunes, I was losing power to front axle while under power! Started out fine, with 4wd (it was set to 4 High Part Time & Tazer was in Force AWD mode), but the front end would lose drive when I was higher in the revs. It really sucked on the hills. This video shows it, pay attention to the roost off the front tires, you’ll see it just stop. I used an infrared thermometer and the exterior Tcase temps where similar to the transmission (170 range)

Anyone else have similar issues? Any suggestions?

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[TheBirdie72]

Guess you should’ve bought a lowly two door sport!

A pity that some people never learn… power isn’t everything…

Oh wait…wrong forum.

 

[AcesandEights]

Dumb question, but you don't have traction control engaged (it's turned off), right?

...and gawd, four-door Jeeps are ugly.

 

[1996cc]

Dumb question, but you don't have traction control engaged (it's turned off), right?

Yes, tried it “off”, then completely off with Tazer, off with Offroad+, and Offroad+ with it on (that turns it “off”). Rear locker on or off. I tried to try everything.

 

[AcesandEights]

Huh, I dunno. Something doesn't seem right.

That's not inherent to the clutches in the full-time system is it? After thinking about it again, no, it has a locked 4wd setting, nvm.

 

[1996cc]

Some DTC codes I have that may be related??

C2226-00
C149E-64
P232A
P032F

Also have a Serv 4wd light now. That’s come and gone in the past though???

 

[RandomSquirrel]

You have codes...and an occasional "Service 4WD" light....I'd get those addressed first; they may be the key to fixing your issue. ;-)

 

[mwilk012]

I thought the 392 didn’t have a 2wd position?

 

[word302]

I thought the 392 didn’t have a 2wd position?

Tazer

 

[6.2Blazer]

I was curious as to how this transfer case works so have been doing some searching around on it. This is the most interesting post I have found.

https://www.4xeforums.com/threads/mp3022-transfer-case-operation-and-monitoring-with-j-scan.2602/

From my experience with other vehicles that have full-time/AWD and part-time/locked 4WD positions it's not unusual for the 4 high part-time mode to not be mechanically locked between the front and rear outputs like a more traditional transfer case. Rather the electronic system just applies more pressure on the clutch pack in the transfer case, but that pressure can be overcome or the clutch packs damaged. Pretty common on 1/2 ton Chevy trucks for years and a well known issue if you used 4 high really hard, especially with bigger tires, that the clutches would eventually start slipping or fail and therefore not always apply power to the front tires. I'm not 100% sure from my reading so far on the JL 392 transfer case but appears that in at least the 4 high part-time position it's just from electronically applied clutch pressure. The above referenced post also seems to indicate that the electronic clutch force may be reduced by the ECM at certain speeds and/or throttle positions. I would be curious if doing the same type of thing in the 4 low mode has the same issues with losing power to the front wheels (which would indicate 4 low was also simply engaged by clutch pressure and not a true mechanical connection).

 

[1996cc]

Thanks for that other post. Super informative. The 392 has the same Tcase as the 4xe and Mojave, just without the 2wd position on the lever. That’s why Tazer is able to enable the 2wd mode, and also why it doesn’t hurt the Tcase to run in that fashion.

 

[Rubigone]

Any reason why you run it in 2h? Even though the 4xe has the same transfer case as you do it also reduces engine power when in 2h, something i suspect your 392 doesn’t. And if i remember correctly it wasn’t because of driveability, it was some components that can’t handle the torque output.

 

[1996cc]

Any reason why you run it in 2h? Even though the 4xe has the same transfer case as you do it also reduces engine power when in 2h, something i suspect your 392 doesn’t. And if I remember correctly it wasn’t because of driveability, it was some components that can’t handle the torque output.

A few reasons. The main one is I currently have an Ultimate Dana 44 front axle out of my last jeep in the front with standard 1410 U joints in the shafts. I don’t want it engaged on pavement since I don’t have CV joints. There’s also the fuel mileage gain, but I’m sure that’s negligible to non-existent since I don’t have unlocking hubs yet. And ultimately I plan to run 1 ton axles and never use 4wd unless offroad. Regarding the components that can’t handle the full power, I’m well aware of that and that’s why I want 1 tons. Really, you’re only talking about the rear ring and pinion and the rear axle shafts. So I’m relatively careful where and when I romp on it. And I do have chromoly rear axle shafts.

 

[mwilk012]

You still have the FAD in place?

 

[1996cc]

Does not exist in the Ultimate 44

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