P1779

DTC P1779

Circuit Description
Engine torque information is sent to the transmission control module (TCM) by the engine control module (ECM) through the controller area network (CAN). A two-wire circuit is used to communicate data between the ECM and TCM, CAN H and CAN L. A fault in the CAN will not cause DTC P1779 to set by itself. If a communication fault occurs, other DTCs will set before P1779.
When the ECM sends the TCM an invalid engine torque, DTC P1779 sets. DTC P1779 is a type A DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1779 Torque Delivered Signal

Conditions for Running the DTC
No other CAN errors are present.

Conditions for Setting the DTC
The engine torque is invalid for 1 second.

Action Taken When the DTC Sets
^ The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
^ The TCM commands maximum line pressure.
^ The TCM freezes transmission adaptive functions.
^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as Freeze Frame and Failure Records.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
^ The TCM stores DTC P1779 in TCM history.

Conditions for Clearing the MIL/DTC





^ The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
^ A scan tool can clear the MIL/DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an 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.

Diagnostic Information and Procedures



DTC P1780
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 delaying 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 P1780 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P1780.
When the TCM receives a torque reduction failure message from the ECM, DTC P1780 sets. DTC P1780 is a type C DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1780 Torque Reduction Signal

Conditions for Running the DTC
^ No other CAN errors are present.
^ The engine run time is greater than 5 seconds.

Conditions for Setting the DTC
The ECM notifies the TCM that a torque reduction request has failed for 1 second.

Action Taken When the DTC Sets
^ The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL).
^ The TCM requests the ECM to illuminate the service vehicle soon (SVS) lamp.
^ The TCM commands maximum line pressure.
^ The TCM freezes transmission adaptive functions.
^ The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
^ The TCM stores DTC P1780 in TCM history.

Conditions for Clearing the SVS Lamp/DTC





^ The TCM clears the SVS lamp request when the condition no longer exists.
^ A scan tool can clear the SVS Lamp/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.