2015 JKU Auto P0734 Issue in 4wd only:

[stevewix]

Gents, I need help diagnosing a P0734 code as well as P0733. It's an automatic, but codes only arise when the vehicle is either manually commanded to 4th or 5th or allowed to shift automatically (MPH threshold?). The codes started popping up immediately after installing a set of Dana Spicer Ultimate 60s with 5.38 gears and 40" tires. I need some ideas and will be posting freeze data.

 

[wayoflife]

Did you make sure to calibrate your speedometer/set your gear ratio and tire size with a ProCal or the like after you installed your axles? This is REQUIRED on a 2012-up JK.

 

[stevewix]

Did you make sure to calibrate your speedometer/set your gear ratio and tire size with a ProCal or the like after you installed your axles? This is REQUIRED on a 2012-up JK.

I specifically used a Procal to do this, but I'll have to hook up the scanner again and verify the changes were accepted. The code only pops up in 4hi or 4low.

 

[wayoflife]

I specifically used a Procal to do this, but I'll have to hook up the scanner again and verify the changes were accepted. The code only pops up in 4hi or 4low.

Hmmm, sounds to me like you might have mismatched gears in your axles. Wouldn't be the first time I've seen it. Might need to pull the diff covers and verify what ratio is installed in each.

 

[stevewix]

Hmmm, sounds to me like you might have mismatched gears in your axles. Wouldn't be the first time I've seen it. Might need to pull the diff covers and verify what ratio is installed in each.

Before I lose the brand new gear lube in the front, if the gears were mismatched I would get a grinding noise as I shifted the t-case with the hubs locked followed by at least a slight to moderate power-sapping bind, right?

 

[WJCO]

Before I lose the brand new gear lube in the front, if the gears were mismatched I would get a grinding noise as I shifted the t-case with the hubs locked followed by at least a slight to moderate power-sapping bind, right?

Usually you would get some tcase noise. You could also jack up the jeep, chalk the tire in a certain spot and spin it by hand. Count the # of times the drive shaft makes a full rotation. If your DS rotates 4 times while your tire goes around once, you have 4.10 gears. Do that with both axles and see if they're the same.

 

[wayoflife]

Before I lose the brand new gear lube in the front, if the gears were mismatched I would get a grinding noise as I shifted the t-case with the hubs locked followed by at least a slight to moderate power-sapping bind, right?

Not necessarily. At least, you most likely won't hear any grinding as you shift into 4WD. You could probably even move about 10 feet or so before your t-case would let you know how unhappy it was. Instead of draining your diffs, you could always mark your drive shaft and tire and slowly roll it forward. Count the amount of rotations you see on the drive shaft to equal one full rotation of your tire. You should see approximately the same of rotations as your gears. Check the rear and then the front with the hubs locked. If there's a difference, you have a problem.

 

[wayoflife]

Usually you would get some tcase noise. You could also jack up the jeep, chalk the tire in a certain spot and spin it by hand. Count the # of times the drive shaft makes a full rotation. If your DS rotates 4 times while your tire goes around once, you have 4.10 gears. Do that with both axles and see if they're the same.

LOL!! Beat me to it. :crazyeyes:

 

[wayoflife]

Update:. I did a bit of everything today. Topped off atf, which was slightly low. Changed from 40" tires to an old set of 37s, reflashed the gear ratio with the procal, and did a lot of watching live data on the autel. P0731-p0735 are defined above as a comparison of tiss 1 (n2) and tiss 2 (n3). Sensor n3 works intermittently while driving and cuts out completely above 10mph in low range. I've also noticed a tapping solenoid sound in park once the code has been set. Tapping goes away with a key cycle. It's worth a case of beer if any Mopar techs can point me in the right direction.

:cheesy: All that and you didn't even take any time to see if you're gear ratios were the same.

Good luck solving your problem - I'm out :crazyeyes: