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 drive motor generator power inverter module assembly (PIM) contains capacitors and a resistor circuit intended to discharge the electrical energy stored within the capacitors. Whenever the high voltage contactor relays are opened, the HPCM connects an internal resistor circuit across the high voltage positive and negative circuits. If high voltage is monitored by the HPCM after the resistor circuit has been connected, the HPCM commands the motor control modules (MCMs) to connect the motor phase circuits across the DC high voltage (HV) positive and negative circuits. If high voltage is monitored by the HPCM after the motor phase circuits have been connected, indicating a stuck-closed contactor, this DTC will set.