GM Service Manual Online
For 1990-2009 cars only

Displays Test

Certain instrument panel cluster (IPC) features are tested when the ignition is turned on in order to verify that the features are working properly. The following indicators illuminate briefly at key up:

    • ABS
    • Air bag--Flashes 7 times
    • Brake system
    • Charging system
    • Change Engine Oil
    • Engine Coolant Temperature
    • High beam indicator
    • Low Coolant
    • Low Fuel
    • Low oil pressure indicator
    • Low Traction indicator
    • Malfunction indicator lamp (MIL)--Check engine
    • Reduced Engine Power indicator
    • Security indicator
    • Service Vehicle Soon indicator
    • Traction off
    • Upshift indicator (manual transmission)

Indicators and Warning Messages

Refer to Indicator/Warning Message Description and Operation .

Engine Coolant Temperature Gage

The engine control module (ECM) sends coolant temperature as determined by the coolant temperature sensor to the body control module (BCM) via the controller area network (CAN) serial data. The instrument panel cluster (IPC) displays the engine coolant temperature with the gage when the BCM sends a class 2 message to the IPC indicating coolant temperature percentage. The engine coolant temperature (ECT) gage defaults to cold (0°) or below if:

    • The ECM detects a malfunction in the ECT sensor circuit.
    • The IPC detects a loss of class 2 communications with the BCM.
    • The BCM detects a loss of CAN communications with the ECM.

Fuel Gage

The engine control module (ECM) sends fuel level percent to the body control module (BCM) via the controller area network (CAN) serial data. The instrument panel cluster (IPC) displays the fuel level as determined by the BCM. The fuel gage defaults to E (empty) if:

    • The ECM detects a malfunction in the fuel level sensor circuit.
    • The IPC detects a loss of class 2 communications with the BCM.
    • The BCM detects a loss of CAN communications with the ECM.

When the fuel level is less than a pre-determined value, the Low Fuel indicator message illuminates.

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.

Speedometer

The instrument panel cluster (IPC) displays the vehicle speed based on the information from the body control module (BCM). The engine control module (ECM) calculates the vehicle speed based on the controlled area network (CAN) serial data message indicating the wheel reference speed from the electronic brake control module (EBCM). The ECM sends a CAN serial data message to the BCM indicating the vehicle speed. The BCM sends a class 2 message to the IPC indicating the vehicle speed.

The speedometer defaults to 0 km/h (0 mph) when any of the following occur:

    • The EBCM detects a malfunction in the vehicle speed sensor circuit.
    • The ECM detects a loss of CAN communications with the EBCM.
    • The BCM detects a loss of CAN communications with the ECM.
    • The IPC detects a loss of class 2 communications with the BCM.

Tachometer

The instrument panel cluster (IPC) displays the engine speed as determined by the body control module (BCM) via a class 2 message. The engine control module (ECM) determines the engine speed and sends a controlled area network (CAN) serial data message to the BCM indicating the engine speed. The tachometer will default to 0 RPM if:

    • The ECM detects a malfunction in the engine speed sensor circuit.
    • The BCM detects a loss of CAN communications with the ECM.
    • The IPC detects a loss of class 2 communications with the BCM.

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.