Circuit/System Description
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The PSCM monitors vehicle speed validity message from the engine control module (ECM) via the serial data circuit. The power steering control module (PSCM) uses this vehicle speed message, along with the torque sensor and motor rotational sensor inputs, to determine the desired amount of steering assist.
The PSCM monitors the intermediate voltage power limit request message from the accessory power module (APM) to detect a possible overheating event. The hybrid control module (HCM) sends this message to the PSCM via the serial data gateway module to reduce the APM power output to the PSCM until the APM returns to normal operating temperature.