Odometer: Description and Operation

ODOMETER
The odometer shows how far the vehicle has been driven, in either miles (domestic) or kilometers (export). The odometer is shown on display when any of the following occur:
- Ignition is in ACC
- Ignition is in RUN, with no messages On
- The trip reset stem is pressed with the ignition OFF

Odometer readings are displayed in the instrument panel cluster (IPC) based on a class 2 message from the body control module (BCM). The engine control module (ECM) calculates the distance traveled from the vehicle speed sensor (VSS) input. The BCM receives a controlled area network (CAN) serial data message from the ECM and stores the current mileage.

The IPC stores the last valid odometer reading from the BCM in non-volatile memory. When a new valid odometer reading is received from the BCM, the IPC will update the display and store the new reading.

The IPC also receives class 2 messages from the BCM regarding VIN and vehicle content information. Valid information is stored in non-volatile memory at the first key-up with a new IPC. If the VIN or option content do not match the stored information, the odometer will display ERROR.

TRIP ODOMETER
Trip odometer readings are calculated by the instrument panel cluster (IPC) based on the odometer reading received through a class 2 message from the body control module (BCM). The trip odometer is shown when selected with the odometer trip reset stem. To reset the trip odometer, press and hold the trip reset stem for about 2 seconds, until the trip odometer shows zero.