Allison Automatic Transmission

ALLISON AUTOMATIC TRANSMISSION

DTC P0741
Circuit Description for Allison Automatic Transmission
The transmission control module (TCM) uses data from the engine speed sensor and the input speed sensor (ISS) to calculate torque converter slip value. The TCM then compares this calculated slip value to a preset value in the TCM calibration.

DTC P0741 is a type B DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0741 Torque Converter Clutch (TCC) System - Stuck Off

Conditions for Running the DTC
^ DTC P0716, P0717, P0721, P0722 and P0743 are not active.
^ The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts.
^ Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds.
^ The throttle position is in the 10-90 percent range.
^ The transmission must be in forward range.
^ The torque converter clutch (TCC) is enabled.

Conditions for Setting the DTC
DTC P0741 sets when the TCM detects one of the following conditions:
^ A TCC slip value greater than 80 RPM for 15 seconds.
^ The TCC slip speed values indicate a stuck off state.

Action Taken When the DTC Sets
^ The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
^ DTC P0741 will be stored in TCM history.
^ The TCM freezes shift adapts.
^ The TCM inhibits TCC engagement.

Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.

Diagnostic Aids
^ Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions:
- A bent terminal
- A backed-out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation
^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
^ You may have to drive the vehicle in order to experience a condition.

Test Description





The numbers below refer to the step numbers on the diagnostic table.
2. This step tests ignition voltage.
3. This step tests for TCC enable status.