2012 Jeep JKU Automatic Stalling and not going into gear

[Colorado4x4]

Dang, the transmission needs replacing?! Mine has been stalling out in reverse when cold for a few years now. It’s only got 100,000 miles on it. I’m going to try and live with it for a few more years till I can get the money saved for an LT1 lol it doesn’t get driven very much right now anyways.

Mine is a 2016 with 87,000 miles and it is pulling that bullshit, well it stalled for the first time the other day when it was cold out while shifting to reverse. It has always made a weird RPM drop when shifting into reverse, the RPMs drop too low but it finally died the other day. I did check my battery and it was 12.1 V (4 year old battery), so I swapped it out with a new battery and it hasn’t died since but I don’t know what the shit that is about. I’m going to swap out the cam and crank sensors tomorrow hopefully.

 

[AgBass01]

isn't that a replaceable sensor that mounts onto the transmission?

do you have a programmer tune on it for tire size or anything else?

It has been updated for tire size and 4.56 gears. I would hope that they aren't taking advantage of me when it could just be a sensor. This is my local shop that I have used for several years and am good friends with the owner.

 

[AgBass01]

Dang, the transmission needs replacing?! Mine has been stalling out in reverse when cold for a few years now. It’s only got 100,000 miles on it. I’m going to try and live with it for a few more years till I can get the money saved for an LT1 lol it doesn’t get driven very much right now anyways.

Yea I hear ya, I'm at 150K miles and it is my daily driver so I had no other option. As much as I'd love to do a Hemi and 8 speed, I just couldn't justify 30K for that right now. I just need it back on the road.

 

[jeeeep]

It has been updated for tire size and 4.56 gears. I would hope that they aren't taking advantage of me when it could just be a sensor. This is my local shop that I have used for several years and am good friends with the owner.

hopefully not.

I went thru similar transmission issues with my JKU, shifted hard, couldn't drive over 25 mph or it would buck and die.

Took it to a local shop, they couldn't find anything physically wrong, just codes (I can't remember what they were) so they sent the transmission out to another shop for their input and they also confirmed nothing wrong with the transmission and suspected it was something with the communications from the Jeep, luckily none of them charged me.

Limped it home and decided to remove the Superchips tune and return it to stock, including tire size and gears, did a full reset of the electrical by disconnecting the pos and neg from the battery for 24 hours (later found info on how to do it faster).
After 24 hours, connected the battery, started it and shifted thru the gears without moving, shut it down then reinstalled the tune for gears and tires. Haven't had an issue since.

 

[Jsouder53]

Mine is a 2016 with 87,000 miles and it is pulling that bullshit, well it stalled for the first time the other day when it was cold out while shifting to reverse. It has always made a weird RPM drop when shifting into reverse, the RPMs drop too low but it finally died the other day. I did check my battery and it was 12.1 V (4 year old battery), so I swapped it out with a new battery and it hasn’t died since but I don’t know what the shit that is about. I’m going to swap out the cam and crank sensors tomorrow hopefully.

Mines a 2016 as well and I had my battery changed out not that long ago as well. Still happens when it is cold starting. I have to keep the rpm’s high and basically drive it like I’ve never driven a manual.

Yea I hear ya, I'm at 150K miles and it is my daily driver so I had no other option. As much as I'd love to do a Hemi and 8 speed, I just couldn't justify 30K for that right now. I just need it back on the road.

Makes complete sense needing to get it back on the road. I sure hope it stops stalling on you!

 

[007Duc]

Heard back from the shop yesterday afternoon and it is the transmission, torque converter checks out ok, there is an active trouble code for output speed shaft and they say the transmission needs to be replaced.

The speed sensors are part of the conductor plate on the valve body. If you are comfortable pulling the valve body off, the conductor plate is easy to change, and prone to trouble from what I’ve heard on other vehicles that run this trans. Here’s a kit to change it.

Mercedes 722.6 Conductor Plate Transmission Service Kit - OE Supplier 7226CSK

Mercedes 722.6 Conductor Plate Transmission Service Kit - OE Supplier 7226CSK

www.fcpeuro.com

By the way, the 722.6 is just Mercedes designation for our NAG1

 

[007Duc]

Also of note, I just went through a NAG1 debacle, which is how I learned about the above info, but my issue was a persistent P0743 code. Which is the TCC (torque converter clutch) solenoid circuit. I rang out the wiring and found that good. Then, replaced the TCC solenoid in the valve body. As well as changed my fluid and filter. The problem persisted causing the transmission to stay in Limp Mode. I have since replaced the TCM (transmission control module), also something I’ve learned is a major source of faults, under the driver dash. That seems to have corrected my problem, least for the time being, until I get more miles on it to be sure it’s gone for good.

I would definitely explore these possibilities before a complete transmission rebuild/replacement as from a mechanical perspective they (the NAG1) aren’t too bad a transmission. If they only shifted bettper and had 8 spds!

 

[AgBass01]

Well I got the jeep back yesterday and so far no issues. The shop already had it so I let them go ahead and just replace the entire transmission and torque converter. Now that I have a new transmission in there I realize how sloppy my shifts were before. On the bright side I now have 3 yr 100k mile warranty on my transmission.