Serial Data Power Mode Control

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

Modules that depend exclusively on serial data messages for power modes stay in state dictated by last valid PMM message until engine run flag status on serial data circuits can be checked. If PMM fails, modules monitor serial data circuit for engine run flag serial data. If engine run flag serial data is True, indicating engine is running, modules fail-safe to RUN power mode. In this state modules and their subsystems can support all operator requirements. If engine run flag serial data is False, indicating that engine is not running, modules fail-safe to OFF-AWAKE power mode. In this state modules are constantly checking for a change status message on serial data circuits and can respond to both local inputs and serial data inputs from other modules.