Not to sound like a jackass, but how did you check the tranny fluid? Was the engine running? Some people are unaware that the motor should be running to check transmissions.

Also, did you give it the sniff test? What color was the fluid?

 

Checked it running cold and running hot. Both times it checked between the 2 marks. Fluid is still red and smells like transmission fluid.

 

How many miles? Have you had it serviced in it's life yet? The NAG1 is pretty bulletproof behind the 3.6, fluid getting low or burnt is about the only real problems we see on the forum. Wheel speed sensors can make it act funny, but those would throw a warning light.

 

66K miles. Bought it from a one owner 5 months ago. This is the first issue I've had.

 

Welcome to the Forum!

 

It shouldn't need serviced yet under normal driving. Do you know if the PO wheeled it at all? You may want to consider doing a fluid replacement just for piece of mind at that mileage.

 

I bought it from a 60 yo lady that lived in town. Doubt it ever saw a dirt road.

 

Have you recently installed new or larger tires or are there larger than stock tires on it?

 

Yes. We just put on some JL take offs with 33's and the tpms sensors don't work.

 

Welcome to the Forum!
You may have a Torque converter, starting to fail. I would start by getting the trans serviced, and looking in the pan, for material.

 

The larger tires could cause a mis-match between expected speed and actual speed. It should throw a light for that, though. But if it is repeatable on a timer, then that could be the issue. Can you see about getting jscan or one of the other programmers and set your tire size? Though I have not reset my tire size when I change between stock rubicon size to 33s and have not had any issues.

 

The larger tires could cause a mis-match between expected speed and actual speed. It should throw a light for that, though. But if it is repeatable on a timer, then that could be the issue. Can you see about getting jscan or one of the other programmers and set your tire size?

I actually have a jscan. I didn't change tires because I have always ran larger tires on all my vehicles and have never had any issues. I may try changing it though. Thanks

 

When you said the part about the "back up camera was on like it thought it was in reverse" that is a shifter output to the can bus saying "we are in reverse turn on backup camera" along with all other things that go with being in reverse.

Possible hall effect sensor errors or harness issues at shifter. look at jscan, modules, shifter or transmission control, live data pids for status of shifter when issue occurs.

Short pdf from nag1 equipped jk's attached

 

Thanks. Will do

 

I was reading through the PDF you provided and it talks about the under voltage limp mode where if the TCM detects a voltage drop below 8.5 that it will put the jeep into temporary limp mode. Just curious, is it possible that wrong size tires could eventually lead to issues with voltage?

 

I can't see how tire size would affect voltage on the system as the primary electrical system is 12 volts nominal and more between 13 and 14 in operation. some of the logic circuits operate on a 5v level for sensor feed back but it is derived from the primary voltage system and reduced down. In general if you know something is mismatched, such as expected tire size vs actual tire size you should correct it so the vehicle systems have correct data as this can affect shift points.

I reread your post and may have misunderstood the rear camera coming on, if it came on only when the shifter was in the reverse position, then it is working properly. It should not be on in any other positions. Also if memory serves limp mode will put you in second so you can "limp" home. Errors more severe can shut it down but those will set codes almost always.

I have attached on this forum previously the nag1 w5a580 Mercedes 722.6 student manual on the trans and will attach here as well. Southern Illinois university has some excellent youtube vids on 722.6

for overhaul and also same teacher covers individual sections. The design goes back to 1999 or so and its used in everything from sprinter vans, trucks, wk and jk jeeps, to Mercedes sedans. It is a solid design.

 

Sounds like the same thing that was happening to mine back in November and December. In January I drove to the store - just a 10 mile drive and on the way home it lost gear as I was shifting from 2nd to 3rd. Engine was still running but no gears would engage because the clutch itself along with a number of other parts were completely burnt up. $4,000 in repairs and it drove fine for a bit but has started doing the same thing again.