The clutch for lock-up has jammed in the closed position
Contact an Allison dealer.
What you'll see
No driver-visible symptom recorded.
System reaction
The Allison fault code number is: P0741.The fault code is set when the control unit detects that the torque converter lock-up clutch slips more than 150 rpm for more than 25.5 seconds.For the fault code to be set, the following conditions must be met: The engine speed is higher than 200 rpm.Forward gear changing range selected.Accelerator pedal depressed more than 75%.The oil sump temperature is between 25°C and 130°C.More than 6 seconds must have elapsed since the lock-up locked in a gear.The fault code is cleared automatically, when the vehicle has completed 40 start-up cycles without the fault being detected again.
Diagnostic depth
The control unit has detected that the torque converter lock-up clutch is slipping.
Possible fault on the solenoid which controls the lock-up.