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 for 3 seconds:

    • The ABS indicator
    • The Charge indicator
    • The BRAKE indicator
    • The CHECK GAGES indicator
    • The GATE AJAR indicator
    • The LOW FUEL indicator
    • The Park Brake indicator
    • The SECURITY indicator
    • The SERVICE 4WD indicator
    • The SHIFT indicator
    • The TOW / HAUL indicator
    • All gages sweep to their minimum physical position and then to their actual physical position.

The following indicators illuminate for the specified times:

    • The AIR BAG indicator flashes 7 times.
    • The Fasten Safety Belt indicator illuminates for 20 seconds followed by 55 seconds of flashing with the drivers seatbelt unfastened, or, the Fasten Safety Belt indicator will illuminate for 8 seconds with the drivers seatbelt fastened.
    • The SERVICE ENGINE SOON (MIL) indicator illuminates and remains on.

Indicators and Warning Messages

Refer to Indicator/Warning Message Description and Operation .

Engine Coolant Temperature Gage

The IPC displays the engine coolant temperature as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the engine coolant temperature. The engine coolant temperature gage defaults to 100°F (40°C) or below if:

    • The PCM detects a malfunction in the engine coolant temperature sensor circuit.
    • The IPC detects a loss of class 2 communications with the PCM.

Engine Oil Pressure Gage

The IPC uses the engine oil pressure sensor signal to determine the engine oil pressure. The oil pressure sensor signal circuit is solely dedicated to the IPC. The engine oil pressure sensor signal to the IPC is a variable resistance ranging from 0-90 ohms. A sensor resistance of 1 ohms will display as 0 psi (0 kPa) and a resistance of 88 ohms will display as 80 psi (550 kPa).

Fuel Gage

The IPC displays the fuel level as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the fuel level percent. The fuel gage defaults to empty if:

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

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

Odometer

The IPC contains a season odometer and a trip odometer. Momentarily press the trip/reset switch on the IPC in order to toggle between the season odometer and the trip odometer. Press the trip/reset switch for greater than 2 seconds, while the trip odometer is displayed, in order to reset the trip odometer.

The IPC displays the vehicle mileage and trip mileage as determined by the IPC. The IPC calculates the mileage based on the vehicle speed signal circuit from the PCM. The odometer will display 'error' if an internal IPC memory failure is detected.

PRNDL Display

The IPC displays the selected gear position as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the gear position. The PRNDL displays blank if:

    • The PCM detects a malfunction in the transmission range switch circuit.
    • The IPC receives a class 2 message indicating the park position and the column park switch indicates a position other than park such as an open input.
    • The IPC detects a loss of class 2 communications with the PCM.

Speedometer

The IPC displays the vehicle speed based on the information from the PCM. The PCM converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The IPC uses the vehicle speed signal circuit from the PCM in order to calculate the vehicle speed. The speedometer defaults to 0 km/h (0 mph) if a malfunction in the vehicle speed signal circuit exists.

Tachometer

The IPC displays the engine speed based on the information from the PCM. The PCM converts the data from the engine speed sensor to a 2 pulses/engine revolution signal. The IPC uses the engine speed signal circuit from the PCM in order to calculate the engine speed. The tachometer defaults to 0 rpm if a malfunction in the engine speed signal circuit exists.

Voltmeter

The IPC displays the system voltage as detected at the ignition 1 voltage input of the IPC. When the engine is ON, the gage should be between 10 and 16 volts.