Instrument Cluster Circuit Description Description and Operation

When an error occurs in the serial data (class 2) communication between the instrument cluster and the Antilock Brake System (ABS), the ANTI-LOCK indicator is turned on.

When an error occurs in the serial data (class 2) communication between the instrument cluster and the Body Control Module (BCM), the SERVICE VEHICLE SOON indicator is turned on.

When an error occurs in the serial data (class 2) communication between the instrument cluster and the Powertrain Control Module (PCM), the following will happen:

The antilock warning indicator is controlled by the Electronic Brake Traction Control Module (EBCM) over the Class 2 serial data link. The EBTCM will turn the indicator on for approximately three seconds during engine start-up for a bulb check. The EBTCM will flash the ABS warning indicator to warn the driver that an ABS malfunction exists which may have degraded base brake performance. A solid (not flashing) ABS warning indicator warns the driver that a problem has been detected that affects the operation of ABS (ABS may be disabled), but normal brake performance will remain. Refer to General System Description in Antilock Brake System for more information.

The AIR BAG warning indicator is controlled by the Inflatable Restraint Sensing and Diagnostic Module (SDM) by sending a ground signal through circuit 358. The SDM will turn the indicator on for approximately three seconds during engine start-up for a bulb check. The SDM will turn the indicator on to warn the driver of a Supplemental Inflatable Restraint (SIR) system malfunction, which could potentially affect the operation of the SIR system. Refer to SIR System Operation in SIR for more information.

Transaxle gear position is read from the transaxle range switch by the PCM and sent to the instrument cluster through the class 2 serial data link. The instrument cluster then displays the gear position.

Battery voltage is applied to the BRAKE warning Indicator when the ignition switch is in on or start positions. Three switches are used for the ground path to light the BRAKE warning indicator. When any of these switches closes, ground is provided and the indicator lights.

The park brake switch provides a ground signal to the Daytime Running Lamp (DRL) Control Module when the park brake is applied. This signal is then sent from the DRL control module to the Body Control Module (BCM). When the BCM senses that the park brake is applied, the BCM will convey this information along the class II serial data link to the instrument cluster. The instrument cluster will then light the BRAKE warning Indicator for the time in which the park brake is applied.

The brake fluid level indicator switch closes to light the BRAKE warning indicator with a low brake fluid condition in one of the two hydraulic brake fluid reservoirs. This could be caused by a leak in one of the brake lines. The sensor can be reset to OPEN by refilling the reservoir. However, this should only be done after the hydraulic brake system fault is diagnosed and repaired.

The Electronic Brake Traction Control Module (EBTCM) sends a ground signal through circuit 209 to turn on the BRAKE warning indicator and sets a Diagnostic Trouble Code (DTC) when an Antilock Brake System (ABS) failure occurs that affects base brake operation. During initial start-up, the EBTCM will also ground circuit 209 internally to perform a Bulb Test on the BRAKE warning indicator. Refer to General System Description in Antilock Brake System for more information.

The Powertrain Control Module (PCM) will determine the amount of oil life from various sensors and inputs within the engine control system. Oil life is calculated by the PCM and sent to the instrument cluster through the class II serial data link. When the PCM has determined that an oil life of 0 percent is present, it will inform the driver by turning on the CHANGE OIL indicator. After an oil change, the CHANGE OIL indicator can be reset by:

If the light comes on and stays on for 5 seconds, the system did not reset. The system will need to be reset again.

Charging system data is received from the PCM through the class 2 serial data link. The instrument cluster will illuminate the CHARGE warning indicator during bulb test and when the PCM has determined that an under voltage (11.2 V) or over voltage (16.5 V) condition exists. For more information, refer to Charging System Description in Engine Electrical for more information.

Coolant temperature data is calculated within the PCM. The coolant temp warning indicator is controlled through the class 2 serial data line by the PCM. The instrument cluster will illuminate the coolant temp warning indicator when the PCM has determined that the engine coolant temperature has reached a value of approximately 124°C (255°F). Refer to Powertrain Control Module Description in Engine Controls for more information.

The PCM sends a signal through the serial data link (class 2) whenever the cruise control is activated. Refer to Cruise Control System Circuit Description in Cruise Control for more information.

When turning the headlamp switch to PARK or HEAD, the display steps dim to maximum brightness in the dim mode. Further dimming is controlled by the PWM dimming signal of the I/P lamp dimmer switch. The display goes blank when turning the I/P lamp dimmer switch to its lowest position.

Coolant temperature data is sent from the PCM through the class 2 serial data link to the instrument cluster. The instrument cluster will then compare the temperature data with a sixteen-point look-up table to determine needle deflection. A smooth filter is used to secure a continuous response. The instrument cluster will drive the temperature gauge to cold if the temperature data is lost or if the PCM is in a state of health fault.

Indicates to the driver that the fuel access door is located on the left side of the vehicle.

Fuel level data is sent from the PCM through the class 2 serial data link to the instrument cluster. The instrument cluster will then compare the fuel level data with a sixteen-point look-up table to determine needle deflection. A smooth filter is used to secure a continuous response. The instrument cluster will determine if a low fuel condition is present. In the event of a low fuel condition, the instrument cluster turns on the LOW FUEL indicator. In the event the fuel level data is lost, or the PCM is in a state of health fault, the instrument cluster will drive the fuel gauge to empty.

The high beam indicator is turned on when a ground signal is sent to the instrument cluster through circuit 1200. This signal is generated by the headlamp switch when the headlamp switch is either in the HIGH BEAM or the FTP (Flash To Pass) position. Refer to Lighting System Description in Lighting Systems for more information.

The low coolant indicator receives battery voltage when the ignition switch in the on or start position. The instrument cluster will turn the indicator on for one second during engine start-up for a bulb check. The indicator is grounded by the engine coolant level indicator module when the coolant level in the coolant reservoir is below minimum recommended level.

The low fuel indicator turns on when the fuel level signal to the fuel gage drops below approximately 1/8 tank.

The LOW OIL indicator is controlled through the class 2 serial data link by the Powertrain Control Module (PCM). The PCM will sample the oil level once per ignition cycle at power-up only. To test for low oil level at start-up, one of the following conditions must be present:

1. If the engine coolant temperature was between 15°C (59°F) and 90°C (194°F) at the last key off, the engine coolant temperature at key on must be at least 12°C (22°F) cooler than the engine coolant temperature at the last key off.
2. If the engine coolant temperature was higher than 90°C (194°F) at the last key off, the time between the last key off and present key on must be sufficient to allow the oil to drain back to the sump. If the key is turned back on while the PCM is still powered up, the oil level will not be tested.

The LOW OIL indicator will illuminate when the PCM has determined that a low oil level condition exists, or during a brief period of time when the ignition switch is first turned to the on position for bulb test.

Oil pressure data is received from the PCM through the class 2 serial data link. The instrument cluster turns on the low oil pressure warning indicator during bulb test and when the PCM has determined that the oil pressure does not meet the specified value for the engine. Refer to Powertrain Control Module Description in Engine Controls for more information.

Low traction data is received from the Antilock Brake System (ABS) through the class 2 serial data link. The LOW TRAC indicator is used to alert the driver when the ABS is active. Anytime the Electronic Brake Traction Control Module (EBTCM) determines that the vehicle has entered a braking event where ABS is required, the LOW TRAC indicator will turn on to indicate that ABS is active. Refer to General System Description in Antilock Brake System for more information.

The LOW WASHER FLUID turns on when the windshield washer solvent level switch detects a low fluid level. The windshield washer solvent switch sends a ground signal through circuit 99 to the instrument cluster when a low fluid level is sensed.

The season/trip odometer switch, located on the trip odometer reset switch, toggles the odometer display between season and trip mileage readings.

The seat belt indicator operation is controlled by the Body Control Module (BCM) through the class 2 serial data link. When the BCM detects that the ignition switch is in the on position but the driver seat belt has not been fastened, the BCM sends a signal to the instrument cluster to turn on the seat belt warning indicator. The instrument cluster turns on steadly the seat belt indicator during the first 20 seconds, then it flashes for an additional 50 seconds. Refer to Body Control System Description in Body Control System for more information.

The SECURITY indicator operation is controlled by the Body Control Module (BCM) through the class 2 serial data link. The SECURITY indicator could be turned on continuously or flashing depending on the status of the theft deterrent system. Refer to SECURITY Indicator Description in Theft Deterrent System for more information.

The SERVICE ENGINE SOON warning indicator is controlled by the Powertrain Control Module (PCM) through circuit 419. The PCM turns the indicator on for approximately three seconds during engine start-up for a bulb check. Also, the PCM will illuminate the SERVICE ENGINE SOON warning indicator to warn the driver that an engine control malfunction has been detected which may affect engine performance. Refer to Powertrain Control Module Description in Engine Controls for more information.

The SERVICE VEHICLE SOON warning indicator can be controlled by the Electronic Brake Traction Control Module (EBTCM) or the Powertrain Control Module (PCM) through the class 2 serial data link. The SERVICE VEHICLE SOON warning indicator will turn ON for approximately three seconds during engine start-up for a bulb check. The SERVICE VEHICLE SOON warning indicator will turn on the warn the driver that a malfunction exists within the ABS, PCM or instrument cluster systems which may degrade overall vehicle performance. Refer to General System Description in Antilock Brake System for more information on ABS and refer to Powertrain Control Module Description in Engine Controls for more information regarding the PCM.

The Vehicle Speed Sensor (VSS) is a gear-driven permanent magnet generator housed in the vehicle's transaxle. This sensor generates a sine wave output with a frequency proportional to vehicle speed. The Powertrain Control Module (PCM) converts this signal to an output that is switched to ground at a frequency of 4000 pulses per mile. This signal (circuit 817) drives the speedometer and odometer and is used by other vehicle systems.

The season odometer displays the total accumulated kilometers (miles) of the vehicle. This value is permanently stored in the Electronically Erasable Programmable Read Only Memory (EEPROM) of the instrument cluster. If an odometer malfunction occurs, or if the instrument cluster must be replaced, an authorized Delco® service center must be contacted to program proper vehicle specifics (including mileage) to the instrument cluster.

The trip odometer displays the accumulated kilometers/miles to the tenths of a kilometer/mile since the last reset. This value is stored in Keep Alive Memory (KAM) of the instrument cluster. The trip odometer may be reset by pressing the RESET button on the trip odometer reset switch. If the RESET button is not used to reset the trip odometer, the display will roll over automatically as follows:

The tachometer displays engine speed in revolutions per minute (rpm). Engine rpm data is received from the PCM through the class 2 serial data link. The instrument cluster will then compare the engine rpm data with a sixteen-point look-up table to determine needle deflection. A smooth filter is used to secure a continuous response. The instrument cluster will drive the tachometer gauge to 0 rpm if the engine rpm data is lost, or if the PCM is in a state of health fault.

Traction off data is received from Antilock Brake System (ABS) through the class 2 serial data link. This indicator can be on if the Electronic Brake Traction Control Module (EBTCM) either detects a condition that causes the traction control system to be inhibited, or if the traction control switch is turned off. Refer to General System Description in Antilock Brake System for more information.

The trip reset switch is located on the trip odometer reset switch. When pressed for more than 1.5 seconds, the trip odometer resets to zero.

The instrument cluster receives the signal for turning on the turn signal indicators through circuits 1414 (left turn) and 1415 (right turn). When the ignition switch is in the on position, the hazard warning switch is in the normal position and the turn signal switch is in either the right or left position, the respective turn signal lamp and the instrument cluster indicator will start flashing. If the hazard warning switch is in the HAZARD position, both turn signal lamps and both indicators will start flashing.