This guide explains how to diagnose and repair the Allison 3000 & 4000 Gen5 Torque Converter Clutch (TCC) system when it is stuck off and sets Diagnostic Trouble Code (DTC) P0741.
Related Resources
Diagnostic Response
None
Circuit Description
This test detects excessive lockup slip speed while the TCC lockup is commanded ON. When slip speed is higher than expected, it indicates that the TCC is not applying correctly.
Action Taken When the DTC Sets
- The DTC is stored in the TCM history.
- The CHECK TRANS light illuminates on the dash.
- The TCC (lockup clutch) is commanded OFF to prevent further damage.
Conditions for Clearing the DTC / CHECK TRANS Light
- Use a diagnostic tool (such as Allison DOC GEN5) to clear the DTC from the TCM history.
- The TCM automatically clears the DTC if the vehicle completes 40 warm-up cycles without the fault reoccurring.
Diagnostic Aids
DTC P0741 may be caused by one or more of the following issues:
- Turbine Shaft Speed (TSS) Sensor Circuit
- Faulty or intermittent TSS sensor signal.
- Damaged wiring or poor electrical connection.
- Low TCC or Main Hydraulic Pressure
- Insufficient pressure preventing clutch engagement.
- Control Module / Valve Body Issues
- Stuck or sticky valves.
- Mechanically defective TCC solenoid.
- Broken springs or damaged valve bores.
- Plugged suction filter, damaged gaskets, or excessive internal leaks.
- Transmission Mechanical Problems
- Worn or damaged seals or sealing rings.
- Worn TCC damper or internal mechanical damage.
- Damaged rotating drum (affecting TSS pickup).
- Debris in the transmission or excessive hydraulic leaks.
- TCM (Transmission Control Module) Malfunction
- Internal TCM fault or failure to command proper TCC operation.