Circuit/System Description
WARNING: This page is about a different car, the 2010 GMC Yukon, 2010 Chevrolet Tahoe, and 2010 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
This diagnostic applies to communication integrity conditions between the engine control module (ECM) and the hybrid powertrain control module (HPCM). The HPCM monitors a state of health message that the ECM transmits to verify the ECM is functioning properly.