DT12 TRANSMISSION ISSUES, STUCK IN NEUTRAL (2024)

hey guys,
got a 2016 cascadia here with a dd13 and DT12 transmission, truck was towed in since it wouldnt go into gear, the air pressure builds fine, and when put into drive an audible gear drop is heard with the normal air actuation sound and then it will air actuate again and again and again, the display will stay in neutral and pushing the throttle will do nothing, until it beeps and stops trying to go into gear, reverse will not work either. there are no transmission codes, the range splitters pass actuation thru DDL, but when trying to do a gear shift thru DDL, the control unit will give an unexpected error. not sure what it could be, dont have much experience with these transmissions, thanks

Sticking split pin bushing is a common fault on that model year. You'll have to make and review a log file per the attached file. There's a technical service letter attached that will tell you if this applies to your transmission based on date of manufacture.

looking at the diagnosis steps it might be that, our shop doesn’t use DDL but see what you can make of this, the clutch is cycling but the gear isn’t like the diagnosis steps say it should, check it out

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Yea, that sounds like the conditions listed in the troubleshooting. Your clutch is cycling, your splitter group actuator position stays at 99% the whole time, which I'm assuming is the "high" position it would read in DDDL . And the current gear stays at zero. I'm not familiar with the software you're using, but it sounds like the split pin bushing to me.

Dropped it yday, was a pain with the side shifter offsetting the weight, had to remove the air tanks and everything behind it to lift it out with a forklift, is there going to be physical damage I’ll see to the split pin?

There shouldn't be damage to the pin. Its just that the aluminum bore that the pin slides in wears, and causes the pin to stick. The technical service letter I attached has a part number for the kit you need. If it's the old style, you have to drill out the hole to accept a steel bushing.

I just did a split pin bushing repair, with transmission in truck. Removed battery power. Now the transmission shifts into neutral sometimes and is searching for a gear you can hear it clicking. Then when the speed lowers it will go back into the gear you were in or skip two gears up. I am wondering if the transmission needs to relearn. If so, can I do that myself or a shop. Also is the relearn clutch and shift pattern? The shift controller came off and I disconnected the tcm. So again after split pin bushing repair is a relearn procedure required?

probably do need a relearn procedure, the service manual does state to perform one, you're gonna need a software to do that or its gonna have to be a shop, the learn is both the clutch and gear shifting