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
    • AWD
    • Air Bag--Controlled by the SDM
    • Brake System
    • Charging System
    • Change Engine Oil
    • Door Ajar
    • Engine Coolant Temperature
    • Engine Oil Level
    • Engine Oil Pressure
    • Fasten Safety Belt--Controlled by the SDM
    • Fuel Level Low
    • Hybrid Economy Indicator (L4 Hybrid Only)
    • Low Coolant
    • Malfunction Indicator Lamp (MIL)--Controlled by the ECM
    • Security Indicator
    • Service Vehicle Soon
    • Tire Pressure Low
    • Vehicle Dynamics Caution (VDC)

Indicators and Warning Messages

Refer to Indicator/Warning Message Description and Operation.

Charge/Assist Gage (Hybrid)

The charge/assist gage displays the level of charging or assist (discharge) of the hybrid battery pack. The charge/assist gage displays the charging and discharge activities on the battery intermediate voltage bus. The gage is made up of two separate zones for charge and assist activities. The charge zone displays electric energy flowing to the hybrid battery pack as a result of regenerative braking activity or the vehicle coasting. The assist zone displays electric energy used to boost the vehicle launch flowing out of the hybrid battery pack. The charge/assist gage displays both the magnitude and direction of energy flow on the intermediate voltage bus. When the gage pointer is set in between the two zones, there is no activity on the bus and this indicates a neutral charge state.

Fuel Gage

The instrument panel cluster (IPC) displays the fuel level based on information from the engine control module (ECM). The engine control module (ECM) calculates the fuel level based on information from the fuel level sensor. The engine control module (ECM) sends the fuel level information to the body control module (BCM) via the serial data circuit. The instrument panel cluster (IPC) displays the fuel level as received from 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 serial data communications with the BCM.
    • The BCM detects a loss of serial data communications with the ECM.

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

Speedometer

The instrument panel cluster (IPC) displays the vehicle speed based on information from the engine control module (ECM). The engine control module (ECM) calculates the vehicle speed from the vehicle speed sensor (VSS) input. The ECM sends a serial data message to the BCM indicating the vehicle speed. The instrument panel cluster (IPC) displays the vehicle speed as received from the BCM via serial data circuit.

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

    • The ECM detects a malfunction in the vehicle speed sensor.
    • 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 engine control module (ECM) determines the engine speed and sends the engine speed serial data message to the BCM. The BCM sends the engine speed via the serial data circuit to the IPC. The tachometer will default to 0 RPM if:

    • The ECM detects a malfunction in the engine speed sensor.
    • The BCM detects a loss of serial data communication with the ECM.
    • The IPC detects a loss of serial data communication with the BCM.

Hybrid Tachometer

The hybrid tachometer is a single gage that displays the engine speed and indicates whether the vehicle is in the AUTO STOP or OFF mode of operation. The AUTO STOP mode indicates that the vehicle is still motion capable and the engine could restart by auto start at any time. OFF mode indicates that either the vehicle is turned OFF or the engine has stalled. The instrument panel cluster (IPC) displays the engine speed as determined by the engine control module (ECM). The engine control module (ECM) determines the engine speed and sends the engine speed serial data message to the BCM. The BCM sends the engine speed via the serial data circuit to the IPC. The tachometer defaults to 0 RPM if:

    • The ECM detects a malfunction in the engine speed sensor.
    • The BCM detects a loss of serial data communication with the ECM.
    • The IPC detects a loss of serial data communication with the BCM.