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 hybrid powertrain control module uses the serial data network to signal the engine control module (ECM) that the hybrid system is requesting malfunction indicator lamp (MIL) illumination. A DTC is set in the hybrid powertrain control module and the request for MIL illumination is sent when the hybrid powertrain control module has determined that a failure that affects emissions has occurred in the hybrid control system. When the ECM receives the message from the hybrid powertrain control module, DTC P0AC4 will set in the ECM.