This is from my Allison manual but it is for the 5 speed. Basically the same thing for the 6 speed but i am not sure on pulling the plug. I did it and nothing changed. I am starting to think it may be the c3 clutches but I know the clearance was right when I put them in. I think I am going to have to pull the tranny again.
Limp Home Test
With the ignition in the OFF position (engine not running), the selector in N (Neutral) and the parking
brake set, remove the wiring harness from the main transmission connector. When the engine is
restarted, the transmission will default to a “limp home” capability. In this state, trim solenoid A (deenergized) allows C3 clutch to be applied. If the selector valve is moved to the reverse range position,
main pressure will be routed to C5 clutch, allowing reverse operation. If the selector valve is moved to
the drive range position, main pressure will be routed to C1 clutch, allowing third range operation.
This allows a technician to use “limp home” capability to determine if a hydraulic or an electrical
problem exists. If reverse and third ranges are available in “limp home,” an electrical failure may be
indicated. If only one of the two ranges or neither was obtainable, this may indicate an internal
hydraulic failure (failed clutch, stuck valve, or solenoid failure). The clutches that could possibly have
an indicated failure in “limp home” are C1, C3, and C5
Limp Home Test
With the ignition in the OFF position (engine not running), the selector in N (Neutral) and the parking
brake set, remove the wiring harness from the main transmission connector. When the engine is
restarted, the transmission will default to a “limp home” capability. In this state, trim solenoid A (deenergized) allows C3 clutch to be applied. If the selector valve is moved to the reverse range position,
main pressure will be routed to C5 clutch, allowing reverse operation. If the selector valve is moved to
the drive range position, main pressure will be routed to C1 clutch, allowing third range operation.
This allows a technician to use “limp home” capability to determine if a hydraulic or an electrical
problem exists. If reverse and third ranges are available in “limp home,” an electrical failure may be
indicated. If only one of the two ranges or neither was obtainable, this may indicate an internal
hydraulic failure (failed clutch, stuck valve, or solenoid failure). The clutches that could possibly have
an indicated failure in “limp home” are C1, C3, and C5