Diagnostic Instructions
DTC Descriptor
DTC P2544: Transmission Torque Request Circuit
Circuit Description
To improve shift feel, the transmission control module (TCM) may request that the engine control module (ECM) reduce engine torque during shift events. When such a request is received, the ECM responds by retarding the base ignition timing and notifying
the TCM that the request has succeeded. If the ECM is unable to comply with the request, the ECM sends the TCM a message that the request has failed.
The torque reduction request is sent to the ECM through a communication network called the controller area network (CAN). Two circuits are used to communicate CAN data between the ECM and TCM. A fault in the CAN will not cause DTC P2544 to set by
itself. If a CAN fault occurs, other DTCs will set before DTC P2544.
Conditions for Running the DTC
| • | The engine run time is greater than 5 seconds. |
| • | No other CAN errors are present. |
Conditions for Setting the DTC
The ECM notifies the TCM that a torque reduction request has failed for 2 seconds.
Action Taken When the DTC Sets
| • | DTC P2544 is a Type B DTC. |
| • | The TCM commands maximum line pressure. |
| • | The TCM freezes transmission adaptive functions. |
| • | At the time of the first failure, the TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record. |
| • | At the time of the second failure, the ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame. |
| • | The TCM stores DTC P2544 in TCM history. |
Conditions for Clearing the DTC
| • | DTC P2544 is a Type B DTC. |
| • | The ECM turns OFF the malfunction indicator lamp (MIL) after the sixth consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non emission related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM. |
Diagnostic Aids
This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to
Battery Inspection/Test.
Reference Information
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Circuit/System Testing
Observe the DTCs in the scan tool
| ⇒ | If DTC P0604 is set, replace the ECM. |
| ⇒ | If DTC P0604 is not set, replace the TCM. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for ECM or TCM replacement, programming, and setup
