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:

    • Antilock Brake System (ABS)
    • Air bag -- flashes 7 times
    • Brake System
    • Charging System
    • High beam indicator
    • Liquid crystal display (LCD) Message Center
    • Low oil pressure indicator
    • Malfunction indicator lamp (MIL) -- Check engine
    • Shift indicator
    • Theft System

Indicators and Warning Messages

Refer to Indicator/Warning Message Description and Operation .

Engine Coolant Temperature Gage

The engine control module (ECM)/powertrain control module (PCM) sends coolant temperature as determined by the coolant temperature sensor to the instrument panel cluster (IPC) via class 2. The IPC displays the engine coolant temperature with the gage. The engine coolant temperature gage defaults to cold (0°) or below if:

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

Fuel Gage

The engine control module (ECM)/powertrain control module (PCM) sends fuel level percent to the instrument panel cluster (IPC) via class 2. The IPC displays the fuel level as determined by the ECM/PCM. The fuel gage defaults to E (empty) if:

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

When the fuel level is less than 10 percent, the LOW FUEL message illuminates.

Message Center

The message center is located in the instrument panel cluster (IPC) at the bottom of the speedometer. It is a two-line display that gives the odometer, trip odometer, warning and information messages.

With the key in adaptive cruise control (ACC), the odometer and trip odometer are shown. With the key in RUN, the entire message center liquid crystal display (LCD) is commanded on for a few seconds to check the display segments.

Information or warning messages show in the top line of the message center. Information messages have a higher priority than the odometer. If there are several messages, each message will be shown for a few seconds before the next message is displayed. The list of messages repeats. Each message can be cleared for that key cycle by momentarily pressing the trip reset button when the message is displayed. Several messages will also cause a chime to sound as a driver alert.

When the ignition key is OFF, the odometer and trip odometer can be displayed by pressing the trip reset stem once. The message center will show both odometer readings for a few seconds, then go off.

Odometer

The odometer shows how far the vehicle has been driven, in either miles (domestic) or kilometers (export). The odometer is shown in the top line of the message display when any of the following occur:

    • Ignition is in adaptive cruise control (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)/powertrain control module (PCM) calculates the distance traveled from the vehicle speed sensor (VSS) input. The BCM receives a class 2 message from the ECM/PCM 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 vehicle identification number (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.

Oil Life Monitor Reset

From the Odometer display, momentarily pressing the trip reset button toggles to the oil life reset mode in the instrument panel cluster (IPC). Pressing and holding the button, while OIL LIFE is displayed will reset the oil life monitor in the engine control module (ECM)/powertrain control module (PCM) with a class 2 message. The ECM/PCM responds with a class 2 message to the IPC.

Speedometer

The instrument panel cluster (IPC) displays the vehicle speed based on the information from the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM calculates the vehicle speed based on the class 2 message indicating the wheel reference speed from the electronic brake control module (EBCM) if:

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

The speedometer defaults to 0 km/h (0 mph) if the IPC detects a loss of class 2 communications with both the ECM/PCM.

Tachometer

The instrument panel cluster (IPC) displays the engine speed as determined by the ECM/PCM via a class 2 message. The tachometer will default to 0 RPM if:

    • The engine control module (ECM)/powertrain control module (PCM) detects a malfunction in the engine speed sensor circuit.
    • The IPC detects a loss of class 2 communications with the ECM/PCM.

Trip Odometer

Trip odometer readings are calculated by the instrument panel cluster (IPC) based on odometer reading received from a class 2 message from the body control module (BCM). The trip odometer is shown in the bottom line of the Message Display whenever the odometer is displayed. To reset the trip odometer, press and hold the trip reset stem for about two seconds, until the trip odometer shows zero.