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 has several methods of monitoring the total voltage values of the hybrid batteries. The BECM monitors the calculated battery voltage and the terminal voltage. The calculated voltage represents the sum of the voltages from the 20 individual battery measurements, and the terminal voltage represents the total DC bus voltage as measured on the output side of the high voltage contactor relays. The BECM compares these two voltage readings and looks for a difference. The BECM also monitors the terminal voltage for both over voltage and under voltage conditions.