Circuit Description
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
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 P1779 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P1779.
When the ECM sends the TCM a driver requested torque signal that is invalid, DTC P1779 will set. DTC P1779 is a type A DTC.