Main code 57 indicates failure of the range verification C3 pressure switch test. Range verification C3 pressure switch while in 1st. The test occurs when a range is commanded that does not use the C3 clutch (neutral, 1, 2, 4, and 6). The code is set if the C3 pressure switch is closed when it should be open. If C3 clutch comes on when not needed, three clutches are applied and a transmission tie-up occurs. The ECU will command a range which does not use the C3 clutch and activate the DO NOT SHIFT response.
Allison WTEC II Fault Code: 56 PID: SPN: 77 FMI: Range verification ratio test, R
Allison WTEC II Fault Code: 56 PID: SPN: 66 FMI: Range verification ratio test, 6th
Allison WTEC II Fault Code: 56 PID: SPN: 55 FMI: Range verification ratio test, 5th
Allison WTEC II Fault Code: 56 PID: SPN: 44 FMI: Range verification ratio test, 4th
Allison WTEC II Fault Code: 56 PID: SPN: 33 FMI: Range verification ratio test, 3rd
Allison WTEC II Fault Code: 56 PID: SPN: 22 FMI: Range verification ratio test, 2nd
