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 powertrain control module (PCM)/engine control module (ECM). The IPC receives a GMLAN message from the body control module (BCM) indicating the fuel level volume. The fuel gage defaults to empty (E) if:

    • The PCM/ECM detects a malfunction in the fuel level sensor circuit.
    • The IPC detects a loss of GMLAN 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 GMLAN to the instrument panel cluster (IPC) for display. The BCM calculates and stores the mileage based on the vehicle speed GMLAN message from the powertrain control module (PCM)/engine control module (ECM). The IPC displays the season odometer information from the BCM in the driver information center (DIC). The odometer will display error if the IPC detects an invalid odometer data from the BCM. After an invalid odometer data is received from the BCM, the IPC will display the last known odometer reading for 1.5 seconds before error is displayed in the DIC.

Speedometer

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

    • The PCM/ECM detects a malfunction in the vehicle speed sensor circuit.
    • The BCM detects a loss of GMLAN communications with the PCM/ECM.
    • The IPC detects a loss of GMLAN communications with the BCM.

Tachometer

The instrument panel cluster (IPC) displays the engine speed as determined by the powertrain control module (PCM)/engine control module (ECM). The IPC receives a GMLAN message from the body control module (BCM) indicating the engine speed. The tachometer will default to 0 RPM if:

    • The PCM detects a malfunction in the engine speed sensor circuit.
    • The BCM detects a loss of GMLAN communications with the PCM/ECM.
    • The IPC detects a loss of GMLAN communications with the BCM.

Boost Gage

The boost gage is a measure of the engine manifold air pressure. The powertrain control module (PCM) 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 PCM 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 also turned ON. Refer to Supercharger Description and Operation or Boost Control System Description .