Circuit Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The powertrain control module (PCM) sends a state of health message to the EBCM within 5.5 seconds after the modules are powered up. This message is sent via serial data communications.