Circuit/System Description

The body control module (BCM) calculates the mileage based on the vehicle speed signal circuit from the engine control module (ECM). The BCM then sends a GMLAN serial data message to the instrument panel cluster (IPC) indicating the value of the odometer. The odometer will display 'error' if an internal BCM memory failure is detected. The odometer displays either miles or kilometers and the desired units can be accessed by pressing the trip/reset switch.