Circuit Description
WARNING: This page is about a different car, the 2005 Cadillac STS. 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 P2637 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P2637.
When the ECM sends the TCM an engine torque signal that is invalid, DTC P2637 will set. DTC P2637 is a type B DTC.