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 high voltage (HV) direct current (DC) voltage system is protected by a 125A fuse. The fuse is located in the high voltage manual disconnect lever and can only be serviced by replacing the HV manual disconnect lever. The fuse is positioned between the negative and positive terminals at hybrid battery 11. If the fuse is open or the high voltage manual disconnect lever is removed, the scan tool parameter will display 0 volts for hybrid battery 11. The BECM monitors the high voltage interlock circuit (HVIC) for normal operation along with hybrid battery 11 voltage in order to determine if the high voltage fuse is open. If the fuse is open this could indicate that there may be a short between the positive and negative high voltage DC circuit. The high voltage system is isolated from chassis ground.