Eaton Gen 2 (AutoShift) Fault Code: 74 PID: SID 54 FMI: 12 Failed to Synchronize

Description

Overview:
Fault Code 74 indicates the transmission is unable to use system controls to synchronize during a shift.

Detection:
If there is engine communication on the J1939 Link and the engine does not respond to transmission speed and torque commands, sets the code. Failure of the Inertia Brake system to slow the Input Shaft also sets the code.

Fallback:
If the failure occurs while moving, it could cause a 1-speed fallback. Once the vehicle is stopped, starting gear and reverse gear can be engaged. If the Inertia Brake system failed, it may be difficult to engage a gear from a stop if the Inertia Brake was providing assistance (due to a poorly adjusted clutch).

Possible Causes:
1) Clutch out of adjustment
2) Damaged Input Shaft Brake
3) Inertia Brake
4) Engine Control System

Shop Talk:
Operate vehicle and perform several range up shifts and down shifts in the top gears. If this does not set the code, then perform the following. With vehicle stopped, select a drive gear and fully press clutch pedal. Return transmission to neutral. Repeat several times.