P1781

DTC P1781









Circuit Description with 4L30-E Automatic Transmission
Engine torque information is sent to the Transmission Control Module (TCM) by the Engine Control Module (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 P1781 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P1781.
When the ECM sends the TCM an engine torque signal that is below the lower limit, above the upper limit, or is an unreliable value, then DTC P1781 will set. DTC P1781 is a type C DTC.

Condition for Running the DTC
The ignition is ON.

Condition for Setting the DTC
Engine torque signal is below the lower limit, above the upper limit, or is an unreliable value for 1 second.

Action Taken When the DTC Sets
^ The TCM flashes the sport mode lamp.
^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM records this information as Failure Records.
^ The TCM stores DTC P1781 in TCM history.

Conditions for Clearing the MIL/DTC
^ The TCM stops flashing the sport mode lamp as soon as the fault is no longer present.
^ 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 switch is OFF long enough in order to power down the TCM.