DT12 TRANSMISSION ISSUES, STUCK IN NEUTRAL

I have a 2015 Cascadia with DD13 engine and DT12 automatic transmission. Summer of 2022, its transmission started disengaging whenever the truck hit a pothole (not always, but most of the time). Brought to the dealership three times, they repaired a few things after treatment related such as replacing NOX sensor based on the fact that when the transmission disengaged, the Hill Decent, CEL, and sometimes DPR Re-gen lights all came on. Eventually, they found some grounding (or broken) wires to TCM (I guess).

Now, Spring of 2023, the transmission started disengaging again, even during normal highway driving with the cruise control set. This time the same dealership lowered the transmission and replaced the split pin bushing, clutch, new gasket, new filters, and new fluid. THE ISSUE STILL EXISTS !!!

The only thing is that when the transmission disengages, the engine still runs fine. If you let go of the gas pedal a little (to reduce engine RPM), the gear can usually come back within a split second. Also, the truck shows low air (won't let you engage transmission) first thing in the morning, but it won't show low air afterward.

 

I have a 2015 Cascadia with DD13 engine and DT12 automatic transmission. Summer of 2022, its transmission started disengaging whenever the truck hit a pothole (not always, but most of the time). Brought to the dealership three times, they repaired a few things after treatment related such as replacing NOX sensor based on the fact that when the transmission disengaged, the Hill Decent, CEL, and sometimes DPR Re-gen lights all came on. Eventually, they found some grounding (or broken) wires to TCM (I guess).

Now, Spring of 2023, the transmission started disengaging again, even during normal highway driving with the cruise control set. This time the same dealership lowered the transmission and replaced the split pin bushing, clutch, new gasket, new filters, and new fluid. THE ISSUE STILL EXISTS !!!

The only thing is that when the transmission disengages, the engine still runs fine. If you let go of the gas pedal a little (to reduce engine RPM), the gear can usually come back within a split second. Also, the truck shows low air (won't let you engage transmission) first thing in the morning, but it won't show low air afterward.

 

I have a 2015 Cascadia with DD13 engine and DT12 automatic transmission. Summer of 2022, its transmission started disengaging whenever the truck hit a pothole (not always, but most of the time). Brought to the dealership three times, they repaired a few things after treatment related such as replacing NOX sensor based on the fact that when the transmission disengaged, the Hill Decent, CEL, and sometimes DPR Re-gen lights all came on. Eventually, they found some grounding (or broken) wires to TCM (I guess).

Now, Spring of 2023, the transmission started disengaging again, even during normal highway driving with the cruise control set. This time the same dealership lowered the transmission and replaced the split pin bushing, clutch, new gasket, new filters, and new fluid. THE ISSUE STILL EXISTS !!!

The only thing is that when the transmission disengages, the engine still runs fine. If you let go of the gas pedal a little (to reduce engine RPM), the gear can usually come back within a split second. Also, the truck shows low air (won't let you engage transmission) first thing in the morning, but it won't show low air afterward.

 

Freightliner says this is a common problem with DD12 transmissions built before August 2016. The issue is a split rod bushing.
Service letter No.: 18 TS-2Rev
Detroit DT12 automated manual transmissions may experience difficulty going into gear, especially when the transmission is not at operating temperature. CAUSE: The steel split rod wears on the aluminum transmission housing, causing the split rod to stick. The Shift Controller cannot read the correct position of the split rod and will not shift into gear. To correct this, a hardened steel bushing and new design split rod with three flattened sides were implemented with transmissions built in August, 2016. For Detroit-built transmissions (transmission serial number beginning with 716), the change took place on August 9, 2016, with approximate transmission serial number 716310E0008107. For German-built transmissions (transmission serial number beginning with 715), the change took place on August 29, 2016, with approximate transmission serial number (last seven digits) 1806530

 

I also have the same problem with 2018 Cascadia DD15 with DT-12 transmission. No one tells what’s the problem. Please help to get the right fix.

 

Did you fixed? What was the problem and cost? Thank you!