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 hybrid battery assembly consists of 40 individual batteries. Each battery is rated at 7.2 volts. The batteries are connected together in a series circuit. The BECM monitors and compares these voltages using several different methods. The BECM monitors the hybrid battery voltage on every two batteries for a total of 20 locations, across the battery assembly. The BECM determines the calculated battery voltage by adding the voltage at the 20 locations together. The BECM also multiplies each individual battery voltage measurements by 20. The BECM determines the terminal voltage by monitoring the output voltage from the high voltage contactor relays.