GM Service Manual Online
For 1990-2009 cars only

The instrument cluster is centered above the steering column in the instrument panel and is removable from the rear of the panel (toward the steering wheel).

When an instrument cluster is replaced the law requires either the odometer reading of the replacement unit be set to register the original mileage or that a label be installed on the driver's door frame to show the previous odometer reading and the date of replacement. When a replacement instrument cluster is ordered, a requested odometer value must be supplied.

Service Precautions

The IPC withstands normal current drains associated with vehicle operations. However, use care in order to avoid overloading any of the circuits. In testing for opens or shorts, do not ground or apply voltage to any of the IPC circuits unless instructed to do so by the diagnostic procedures.

Diagnostic System

The IPC has an extensive diagnostic system. The diagnostic system detects and compensates for malfunctions. The system alerts the operator of a malfunction. The IPC displays warning indicators, messages and/or sets a diagnostic trouble codes (DTCs) when the diagnostic system detects a malfunction.

Diagnostic Trouble Codes (DTCs)

The diagnostic trouble codes (DTCs) set in order to indicate that the IPC has detected a malfunction in a particular circuit or other system. The IPC's program follows routines for internal checks, but only under prescribed conditions (Test Conditions). When these conditions exist, the IPC evaluates certain circuits or systems for a malfunction (Failure Conditions). When the failure conditions are true, a DTC is set as a current DTC. Some DTCs command that the IPC illuminate the Service Engine Soon indicator.

The IPC's EEPROM does not store the DTCs. Therefore, the DTCs do not remain after a battery disconnect.

Current DTCs

When the IPC determines that the test conditions and failure conditions for a particular DTC are true, the IPC sets that DTC as current. All of the DTCs remain current at least until the next time the IPC finds the test conditions are true and the failure conditions are false. A few DTCs remain current until the next ignition cycle or until the failure conditions are false several times.

History DTCs

After a DTC has been set, the IPC continues to monitor for the test and failure conditions. For most DTCs, if the test conditions are true and the failure conditions are false, the DTC becomes a history DTC. Some of the DTCs require the test conditions to be true and failure conditions to be false several times. Some of the DTCs require an ignition cycle in order to change from current to history. If no current DTCs are present for a period of 50 ignition cycles, all of the history DTCs clear.

Engine Coolant Temperature Gauge

The engine coolant temperature sensor supplies the engine coolant temperature to the Powertrain Control Module (PCM) via discrete input. The filtered coolant temperature data is sent from the PCM to the IPC, via class 2 serial data messages. The IPC uses the temperature data received from the PCM and a software program to determine the proper coolant temperature to display.

Fuel Level Gauge

A resistive type fuel sender is located in the fuel tank. The fuel sender is connected to the PCM via discrete inputs. The filtered fuel data is sent from the PCM to the IPC, via the class 2 serial data message. The IPC uses the fuel data received from the PCM and a software program to determine the proper fuel level to display.

PRNDL Display

The IPC is equipped with a PRNDL display. The IPC PRNDL information is received from PCM via class 2 serial data message.

Speedometer

A vehicle speed sensor (VSS) signal is supplied by the powertrain control module (PCM) via discrete inputs. The vehicle speed data is sent from the PCM to the IPC through a class 2 serial data message. The VSS discrete signal is pulled up to ignition voltage in the PCM. The IPC uses the VSS data received from the PCM and a software program to determine the proper vehicle speed to display.

Tachometer

The tachometer displays engine RPM (speed), between 0 and 7000 RPM, anytime the power mode is RUN. The engine RPM is calculated by a discrete signal sent to the PCM. The tachometer data is sent from the PCM to the IPC via a class 2 message.

Odometers

Each instrument cluster (IPC) is equipped with a season and 2 trip odometers. The IPC uses the odometer rolling count message from the PCM. The rolling count value is determined by counting the speed pulses from the vehicle speed signal (VSS). The IPC uses the rolling count data from the PCM and a software program to determine vehicle mileage. The odometers can be displayed in miles or kilometers. The units displayed is switched between english and metric by pressing the E/M button on the DID (if equipped). When the E/M button is pressed to show the odometer in metric, km and the number will be displayed. When the odometer is in english, only the number will be displayed. During a bulb check all segments on the odometer including A, B and the word TRIP for 5 seconds.

Season Odometer

The season odometer displays the total accumulated miles or kilometers of the vehicle. This value is permanently stored in the IPC. If an odometer malfunction occurs or if the IPC must be replaced, an authorized Delco service center must be contacted to program proper vehicle specifics (including mileage) for the IPC.

The season odometer is capable of displaying 999,999 kilometers or 999,999 miles depending on units selected. Leading zeros are not displayed. The display will not roll-over to 000,000 if the maximum displayed miles or kilometers are reached. If the display limit is exceeded, the maximum value (999,999) is displayed. If the mileage is above 621,503 miles and metric units are selected the odometer shall display 999,999 km.

Trip Odometer

The trip odometer displays the accumulated miles or kilometers to the tenths of a mile or kilometer since the last reset. This value is stored in the IPC. The IPC has 2 trip odometers which can be selected by pressing the trip reset button. Pressing this button puts you in the trip mode A. Pressing this button again will put you in trip mode B. Pressing this button again will put you in the season (total miles) mode assuming you started from the season mode. The displayed trip odometer is reset on the IPC by pressing and holding the trip reset button for 1.5 seconds. You have to be in the specific trip mode (A or B) in order to reset that specific trip odometer. Both trip odometers accumulate miles or kilometers even when they are not displayed. If the trip reset button is pressed and held for 3 seconds while in a trip mode (A or B), the display will reset to the number of miles (km) travelled since the start of the current ignition cycle.

Indicators

The instrument panel cluster (IPC) indicators illuminate by one of the following methods:

    • The IPC detects a concern with a discrete input.
    • A module sends an indicator illumination request message, via the class  2 serial data line

Several different conditions may illuminate some IPC indicators.

ABS Indicator (ISO Symbol) (Amber)

The ABS indicator may only be ON during RUN. The IPC illuminates the ABS indicator under the following conditions:

    • During the bulb check for 3 seconds.
    • The electronic brake control module (EBCM) sends a class 2 serial data message requesting illumination due to a concern in the ABS system.

AIR BAG Indicator (ISO Symbol) (Red)

The AIR BAG indicator may only be ON during RUN. The IPC illuminates the AIR BAG indicator under the following conditions:

    • The IPC flashes the indicator 7 times (1 per second) during the bulb check.
    • The inflatable restraint sensing and diagnostic module (SDM) sends a class 2 serial data message requesting illumination due to a concern in the SIR system.

Battery Charge Indicator (ISO Symbol) (Red)

The battery charge indicator may only be ON during RUN. The IPC illuminates the battery charge indicator under the following conditions:

    • During the bulb check on the IP reconfigurable telltale message display, it remains displayed (the telltale will remain on as long as the key is in RUN and the engine is not running).
    • The powertrain control module (PCM) sends a class 2 serial data message requesting illumination due to a concern in the charging system.

BRAKE Indicator (Red)

The BRAKE indicator may only be ON during RUN. The IPC illuminates the BRAKE indicator under the following conditions:

    • During the bulb check for 3 seconds.
    • The park brake is on.
    • The brake fluid is low.

Fasten Safety Belt (ISO Symbol) (Red)

The fasten safety belt indicator will be ON during bulb check or in RUN for approximately 70 seconds until the driver's safety belt is latched. The IPC illuminates the fasten safety belt indicator when the driver seat belt is unlatched for 70 seconds. When the driver seat belt is latched the BCM sends a high output to the instrument cluster, which turns the indicator off. If the driver seat belt is unlatched while the vehicle is in RUN the fasten safety belt indicator turns back on for 70 seconds or until the driver seat belt is latched again. There is an audible warning that chimes through the BCM when this indicator is on.

High Beam Indicator (ISO Symbol) (Blue)

The high beam indicator may only be ON during RUN. The IPC illuminates the high beam indicator when the high beam headlamps are on. The headlamp dimmer switch sends a high output to the instrument cluster.

Left Turn Signal Indicator (ISO Symbol) (Green)

The left turn indicator may only be ON during RUN. The IPC illuminates the left turn indicator when the IPC detects a high iput condition from the turn signal switch in the left position. There is an audible warning that chimes through the BCM when this indicator is on.

Rear Fog Lamp Indicator (ISO Symbol) (Yellow)

The rear fog lamp indicator may only be ON during RUN. The IPC illuminates the rear fog lamp indicator when the rear fog lamps are on. The rear fog lamp switch sends a high output to the instrument cluster.

Right Turn Signal Indicator (ISO Symbol) (Green)

The right turn indicator may only be ON during RUN. The IPC illuminates the right turn indicator when the IPC detects a high iput condition from the turn signal switch in the right position. There is an audible warning that chimes through the BCM when this indicator is on.

SERVICE ENGINE SOON Indicator (MIL) (ISO Symbol) (Yellow)

The SERVICE ENGINE SOON indicator may be ON during START and RUN. The SERVICE ENGINE SOON indicator identifies the ready status of the engine's emission system. The PCM activates the indicator with a low side drive circuit through a class 2 message to the IPC. The IPC turns ON the indicator when an emissions related failure is detected by the PCM. The PCM illuminates the indicator during the bulb check.

Messages

The instrument panel cluster (IPC) reconfigurable message display illuminates by one of the following methods:

    • The IPC detects a concern with a discrete input.
    • A module sends a message illumination request message via the class  2 serial data line

If several different messages exist, the messages will display one at a time in 5 second intervals.

CHANGE ENGINE OIL Message (Yellow)

The CHANGE ENGINE OIL Message may only be ON during RUN. The IPC illuminates the CHANGE ENGINE OIL Message when the PCM sends a class 2 message to the IP requesting illumination.

DOOR AJAR Message (Yellow)

The DOOR AJAR Message may only be ON during RUN. The IPC illuminates the DOOR AJAR Message when any door is open. When a door is open that door ajar switch closes sending a low input to the IP.

HOT COOLANT TEMP Message (Red)

The HOT COOLANT TEMP may only be ON during RUN. The IPC illuminates the HOT COOLANT TEMP message when a class 2 message from the PCM indicates the coolant temperature is hot.

LOW COOLANT LEVEL Message (Yellow)

The LOW COOLANT LEVEL Message may only be ON during RUN. The IPC illuminates the LOW COOLANT LEVEL Message when the engine coolant level indicator module sends a low signal to the IP requesting illumination.

LOW ENG OIL LEVEL Message (Yellow)

The LOW ENG OIL LEVEL Message may only be ON during RUN. The IPC illuminates the LOW ENG OIL LEVEL Message when the PCM sends a class 2 message to the IP requesting illumination.

LOW FUEL Message and Fuel Pump (ISO Symbol) (Yellow)

The LOW FUEL message and Fuel Pump ISO are shown on the IP reconfigurable message display.

A resistive type fuel sender is located in the fuel tank. The fuel sender is connected to the PCM via discrete inputs. The filtered fuel data is sent from the PCM to the IPC, via the class 2 serial data message. The IPC uses the fuel data received from the PCM and a software program to determine the proper fuel level to display. If the fuel level is below 9.5% or E, the LOW FUEL message and Fuel Pump ISO illuminate (there is a 30 second delay before the light turns on). The IPC also sends a message to the BCM to chime 4 times when this condition exists.

LOW OIL PRESSURE Message (Red)

The LOW OIL PRESSURE message may only be ON during RUN. The IPC illuminates the LOW OIL PRESSURE message when the PCM sends a class 2 serial data message requesting illumination due to low or failed engine oil pressure. The IPC also sends a message to the BCM to chime continuosly when the condition exists.

OVER SPEED Message (Yellow) (Export)

The OVER SPEED Message may only be ON during RUN. The OVER SPEED Message is internal to the IP. When the vehicle speed reaches 120 km/hr plus or minus 2 km/hr the IPC illuminates the OVER SPEED Message. When the vehicle speed is reduced to 115 km/hr plus or minus 2 km/hr this message turns off on the IP. If the OVER SPEED message is inoperative or always on replace the IPC. Refer to Instrument Cluster Replacement . Make sure you perform the setup procedure for the IPC after replacing the IPC.

REAR HATCH AJAR Message (Yellow)

The REAR HATCH AJAR Message may only be ON during RUN. The IPC illuminates the REAR HATCH AJAR Message when the liftgate is open. When the liftgate is open that liftgate ajar switch closes sending a low input to the IP.

SECURITY Message (Yellow)

The SECURITY message may be ON during any power mode except for START. The IPC illuminates the SECURITY indicator when the security system sends a class 2 serial data message requesting illumination due to concern in the theft deterrent system.