Originally Posted by OurayWK
Hello, yep it sounds like your having the same issue I was having. I was able to get more out of my tech...he gave me the DTC code he pulled from the FDCM: C1438. Apparently this code reference states "transfer case clutch worn" which is the same diagnosis a lot of people get on this forum. My tech did a further pinpoint diagnosis and "found tcase position sensor giving incorrect data, need to replace sensor which is part of shift motor".
I believe the range sensor/ mode sensor/ position sensor are all the same thing. I pretty sure the mode sensor is the part that the wire harness plugs into. You have to replace the whole shift motor to replace the mode sensor. On Rock Auto, it's RETECH Part#UMM1245, $177.89 with a $35 core charge. I also checked the RETECH website and they cover shift motors with a 12mo/12,000 mile warranty which was reassuring. RETECH is a brand by Universal Manufacturing.
All I needed was a socket wrench and a torque wrench - I can't remember what socket size - 10mm I think? Just unbolt and remove the old motor. I used some carb cleaner to clean the mating surface, there was a little dust in there. Then just "add hi-temp grease between the [new] shift motor assembly and the t-case mating surface for seal" - per the service manual. Install the new shift motor by aligning the toothed spline on the shift motor spline. There's only one way it can go on. Add a drop of Loctite 242 to the bolts before re-installing. 242 is the blue medium strength threadlock, also available from Permatech. Torque the bolts to 25-28N-m (18.5-20.5 ft-lbs). I only had an in-lb torque wrench so I made the conversion 234 in-lbs, if I remember right. I was careful to not overtorque the bolts since the t-case housing is aluminum and will strip easily. Plug back in the wire harness and you're done. I shifted into and out of 4low a few times to check that it was working fine. I've had no problems since. Only been 4wheeling once since making the swap, unfortunately. Hopefully I'll get over to Moab soon though, I'm getting spring fever already.
Hope that helps!
Thanks for the info, I just got the Service 4WD System message when I try to pull into 4low. It just worked fine for about 2 months after the N23 recall and now it stopped working....
I just wanted to know if the part number #UMM1245 you order for your Jeep will be the same for my GC 2008 Diesel with QTII?
Thanks in advance for your help.