Circuit/System Description

WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

The drive motor generator battery control module is also referred to as the battery energy control module (BECM). The BECM will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the BECM to the hybrid powertrain control module (HPCM) through the Hybrid LAN communication circuit. The HPCM is the host controller for diagnostic trouble code (DTC) information.

The BECM continuously monitors the system voltage on the ignition 1 voltage circuit. Low or higher than normal ignition voltage may be inadequate for operation of the energy storage components. Improper operation may cause erratic hybrid drive motor battery operation that could include a no start condition. A system over voltage longer than 8 minutes will cause the HV contactor relay coils to get hot. The BECM will send a message to the HPCM to open the contactor relays. The HPCM will open the high voltage contactor relays when vehicle speed is below a calibrated value not close them for 30 minutes in order to allow the contactor relays to cool.