Circuit/System Description
WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The PSCM monitors the engine speed validity message from the engine control module (ECM) via the serial data circuit. The PSCM uses this engine speed message, along with the torque sensor and motor position sensor inputs, to determine the desired amount of steering assist.