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 high voltage crash impact detection (HVCID) sensor utilizes a unidirectional 2-wire circuit. The HVCID modulates current on the interface to send ID, State of Health, and collision status to the serial data gateway module (SDGM). The SDGM serves as a power source and a ground for the HVCID. When the ignition is turned ON and input power from the SDGM is first detected, the HVCID responds by performing internal diagnostics and sending an ID to the SDGM. The HVCID continually communicates status messages to the SDGM, which determines if a fault is present in the HVCID circuit.

The SDGM transmits a GMLAN message to the Hybrid Powertrain Control Module (HPCM) whenever a HVCID sensor fault is detected. The HPCM will then disable the vehicle by opening the high voltage contactor relays until this fault condition is cleared and the HPCM is properly reset.