Circuit Description
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 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.