12 jeep KK service 4wd, transfer case position sensor, gear ratio error

[abowser_kk]

i bought a used jeep KK and I've checked the transmission fluid levels (with a makeshift tool until the original dipstick arrives) and I have added 1 pint of transmission fluid, I changed the oil, and I changed the transfer case motor. I can see using a diagnostic tool that the wheel speed sensors are working. I also tried installing a used transfer case module (although not the exact one that came out of my jeep but another that came out of the same year and model) i then used the diagnostic tool to program it to my Jeep.

However, the Service 4WD light appears only after the jeep tries to shift into second gear. in 4WD High the car goes into limp mode. The car starts normal, then after accelerating it doesn't shift into 2nd gear and goes into limp mode. From there it will shift into 3rd but won't go over 30km/h. In 4WLow, it drives normal but shows service 4WD after switching into 2nd Gear. If i can get it to shift into 2 WD it drives normal but will not shift into 4th and 5th gears. Speed maxes out around 60km/h.

With diagnostic tool i am getting gear ratio errors in 1st 2nd 3rd gears, I am getting erratic information from the transfer case position sensor (and one other transfer case position sensor error) and If i play with the selector long enough i will get an error message saying the FDCM lost communidation with the TCM. I can get it to switch with some trouble between 4WD and 4WLow but it will not enter 2WD.

using the diagnostic tool i notice that in 4WD auto the car does not recognize what gear it is in and reads neutral or information not available after accelerating. The same is true in 4WDLow. Everything is ok until I accelerate and as soon as the gear should shift the diagnostic tool reads information not available under desired gear (or something similar to that, which should show the gear the jeep is in)

can somebody point me in the righ direction to get my jeep repaired.

2012 Jeep KK 2.8 CRD Diesel

 

[rfanslau]

Where are you located my jeep also when doing 60 mph and the rpm drops to 1,700. Meaning in overdrive the car shakes. The transmission shop said it's some toqure lock out problem it goes into the shop March 3rd. Otherwise the car runs great and no engine lights whatever. I will let you know what happens after it get it back. Hope you get yours fixed too
Bob

 

[KJowner]

Check the wiring and plugs

 

[abowser_kk]

So this is an update since I have gotten the problem fixed.

the quick answer is the problem was the transfer case position sensor. The part was around 200€.

I tried first to change the transfer case motor and this made no difference. I then tried changing the transfer case module. Also made no difference.

while changing the transfer case motor i did notice that someone had put a ziptie on the cable running from the transfercase position sensor to keep the cable from moving. I inspected the plug and noticed it had been cracked and the part that clicks when you push it all the way in was no longer there so the sensor clip was not secure in its place. nevertherless i bought a new transfer case position sensor and installed it and initially there was no change but i noticed the clip was slipping out and not staying connected and each time i pushed it in i could here a faint click like the electric was being reconnected. So i took a ziptie and used it to keep the clip in place and every single problem with the car was immediately taken care of and gone.

So doing some research what i think was happening is the transfer case module didn't know what gear the car the was in because it was getting bad reading from the transfer case position sensor...this is why it would not switch from 4wd to 2wd. It was also sending bad information to the transmission module and this was causing the problem with the car not being able to get into the correct gear. I have been driving ever since without a problem.

Sensor was easy to remove...didn't have to lift the car...crawled under it unscrewed three small bolts and it came right off....pay close attention to the size of the bolts and type though because they are easy to strip and do not tighten them down too tight...the correct tool to remove them is a special tool but i used a normal torq wrench very very carefully.

conclusion...it was the wiring all along.

 

[lfhoward]

Nice job figuring that problem out. Glad it is back to normal!