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 the features are working properly. The following indicators illuminate briefly at key up unless otherwise noted:

    • Antilock Brake System (ABS) Indicator
    • Battery Indicator
    • Brake System Indicator
    • Coolant Temperature Indicator
    • Engine Oil Pressure Indicator
    • Tire Pressure Low Indicator

Indicators and Warning Messages

Refer to Indicator/Warning Message Description and Operation.

Fuel Gage

The instrument panel cluster (IPC) displays the fuel level as determined by the engine control module (ECM). The IPC receive serial data messages from the body control module (BCM) indicating the fuel level volume. The fuel gage defaults to empty (E) if:

    • The ECM detects a malfunction in the fuel level sensor circuit.
    • The IPC detects a loss of serial data communications with the BCM.

When the fuel level is less than a certain low percentage, LOW FUEL message displays in the driver information center (DIC).

Odometer

The vehicle odometer is calculated and stored electronically in the body control module (BCM) and is sent via the serial data circuit to the instrument panel cluster (IPC) for display. The BCM calculates and stores the mileage based on the vehicle speed serial data messages from the engine control module (ECM). The IPC displays the season odometer information from the BCM in the driver information center (DIC). If the stored VIN in the IPC matches the stored VIN, the odometer data from the BCM will then be displayed. If the VINs do not match, the IPC will freeze the odometer value for the entire ignition cycle.

Speedometer

The instrument panel cluster (IPC) displays the vehicle speed based on serial data messages from the body control module (BCM). The BCM receives vehicle speed data from the engine control module (ECM) via the serial data circuit. The speedometer will default to 0 km/h (0 mph) if:

    • The ECM detects a malfunction in the vehicle speed sensor circuit.
    • The BCM detects a loss of serial data communications with the ECM.
    • The IPC detects a loss of serial data communications with the BCM.

Tachometer

The instrument panel cluster (IPC) displays the engine speed as determined by the engine control module (ECM). The IPC receives a serial data message from the body control module (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 serial data communications with the ECM.
    • The IPC detects a loss of serial data communications with the BCM.

Boost Gage

The boost gage is a measure of the engine manifold air pressure. The engine control module (ECM) sends a PWM signal to the boost gage indicating the manifold air pressure. The boost gage displays the engine air intake above and below the ambient pressure. The ECM controls the engine boost pressure with the boost control solenoid. The engine boost system pumps more air than the engine would normally use into the intake manifold. The excess air pumped into the intake manifold creates the engine boost effect. The maximum boost pressure is about 83 kPa (12 psi). The boost gage performs a self test by the gage dial moving to 0 kPa (0 psi) when the ignition is turned ON and the boost gage is turned ON.