Allison WTEC II Fault Code: 55 PID: SPN: 97 FMI: Oncoming C3PS test (after shift), NVL to Reverse

Main code 55 indicates the C3 clutch is the oncoming clutch in a shift and the C3 pressure switch did not close at the end of the shift. Oncoming C3PS (after shift), N1?L to R shift

When this code is set, the DO NOT SHIFT response and Neutral with No Clutches is commanded. On the N1 to R shift the transmission is commanded to the previous range. Additional codes could be logged for other shifts where ?X? indicates the range from and ?Y? indicates the range to.

Main code 55 can also be caused by the EEPROM being calibrated for a close ratio transmission and installed in a wide ratio transmission, or vice versa.