The gauges located in the instrument cluster provide the driver with vehicle information. Each gauge utilizes a specific viscosity (thickness) of damping fluid in order to ensure smooth and steady operation of the needle. The instrument cluster controls gauge increments in each gauge by information received on the serial data line or by a dedicated circuit from other systems.

The purpose of illuminating the instrument cluster PRNDL and indicator displays on power up is to verify that segments of the PRNDL and indicator displays are working. The turn signal indicators do not turn ON during this check. Further diagnosis should not be attempted unless all segments do not appear, as this could lead to misdiagnosis. If any portions or segments of the instrument cluster displays are inoperative, the instrument cluster must be diagnosed first.

The check gauges indicator is a LED display located in the instrument cluster. The check gauges indicator turns ON for 3 seconds when the ignition switch is turned to the RUN position. The instrument cluster is constantly monitoring the engine coolant temperature and engine oil pressure when the engine is running. The engine coolant temperature information is sent to the instrument cluster over the Class 2 serial data line by the VCM/PCM. The engine oil pressure information is sent to the instrument cluster from a designated circuit connected to the oil pressure sensor. The instrument cluster will turn the CHECK GAUGES indicator ON if the engine coolant temperature gets too high or if the engine oil pressure gets too low while the engine is running.

The temperature gauge is an analog device that is located in the instrument cluster. The vehicle control module (VCM ) / powertrain control module (PCM) uses class 2 serial data communications in order to inform the instrument cluster of the engine coolant temperature. The instrument cluster operates the temperature gauge in order to appropriately display the engine coolant temperature. The VCM/PCM determines the coolant temperature by measuring current from a variable resistance sensor in the engine coolant jacket with the ignition switch in the RUN position. The sensor changes resistance with coolant temperature. As coolant temperature increases, the resistance of the sensor decreases. The coolant temperature gauge displays temperatures of 160°F, 210°F, and 260°F.

The electronic odometer / tripometer is a display that is located in the instrument cluster. The electronic odometer / tripometer is configured to display miles or kilometers. The season display will increment to a maximum display of 999,999 miles or kilometers. The tripometer display will show a maximum of 9,999.9 miles or kilometers and then will roll over to all zeros. The season display will not roll over to all zeros once the maximum is reached, but will continue to display the maximum miles or kilometers. The tripometer display can be reset by holding the trip button depressed for 2 seconds.

The fuel gauge is an analog device that is located in the instrument cluster. The instrument cluster operates the fuel gauge by the class 2 serial data messages from the VCM/PCM. The fuel gauge indicates the quantity of fuel in the tank when the ignition switch is in the RUN position. When the ignition switch is turned to the OFF, LOCK, START, or ACC position, the pointer may come to rest at any position.

The VCM/PCM measures voltage from a variable resistor inside the fuel tank that is controlled by a float. When the fuel tank is full and the ignition switch is in the RUN position, the resistance is high. The VCM/PCM interprets this signal and sends a message to the instrument cluster indicating the percentage of fuel in the tank over the class 2 serial data line. The fuel gauge indicator then moves to the maximum position or FULL on the gauge face. When the fuel tank is empty, resistance is low. The VCM/PCM interprets this signal and sends a class 2 serial data message to the instrument cluster. The fuel gauge indicator then moves to the minimum position or EMPTY on the gauge face. Failures detected by the PCM/VCM in the fuel gauge signal sends the gauge to EMPTY.

The fuel gauge sender attaches to the top of the fuel tank. A cam lock ring retains the sender. The tank and the sender uses a seal between them.

The sender has three pipes attached to hoses. One pipe is for the fuel feed line. The second pipe connects to the vapor canister. The third pipe is a fuel return line to the fuel tank.

Some senders use a short pigtail connector lead. On other senders, the connector attaches directly to the sender. For diagnostic information, refer to Engine Controls.

The instrument cluster has the capability to display accumulated engine run time hours using the VF display when the cluster is in the LOCK or the ACC position. The hours will accumulate only with the ignition switch in the RUN position and the engine running. The cluster determines and stores the accumulated engine run time hours in a non-volatile format such that if the battery was disconnected or removed from the vehicle the accumulated hours would not change. The cluster will display the accumulated hours when the ignition switch is in the OFF position and the trip reset switch is pushed in and held for more than 4 seconds. The accumulated hours will be displayed for 30 seconds and then turn OFF. The hourmeter will roll over to 0.0 when 10,000 hours are accumulated, and begin to accumulate hours again.

The oil pressure gauge is an analog device that is located in the instrument cluster. The oil pressure gauge is operated directly by the oil pressure sensor circuit only when the ignition switch is in the RUN or START positions. As the engine oil pressure changes, the resistance of the sensor changes and the current flow in the oil pressure gauge causes the needle to move in order to appropriately display the engine oil pressure. A sensor resistance of 1 ohm will display as 0 PSI (0 kPa) and a resistance of 88 ohms will display as 80 PSI (550 kPa). The instrument cluster also monitors the oil pressure sensor circuit and interprets the current flow in this circuit in order to decide when engine oil pressure is too low. The Check Eng Oil Pressure message will be displayed in the message center.

The PRNDL display is a class 2 serial data message to the instrument cluster from the PCM/VCM. The PRNDL display is a vacuum florescent (VF) display which displays the fixed gear position of P, R, N, D, 3, 2, 1 surrounded by a moveable square flag in order to indicate the selected gear position. The position of the moveable square flag is sent to the instrument cluster from the transmission range switch over the class 2 serial data line. The transmission range switch and the neutral safety back up (NSBU) switch operate separately but are incorporated into one part. If the vehicle is equipped with a column shift steering column it will also have a park position switch. The park position switch (if equipped) must also be CLOSED in order for the instrument cluster to display the PARK position. Since the system is entirely electronic, there is not any internal adjustment. The PRNDL display will operate as follows:

Refer to Engine Controls or Transmission/Transaxle for more information about the PRNDL indicator.

The park position switch is only used on vehicles which have a gear shift lever on the column. The park position switch is part of the linear shift assembly in the steering column. The scan tool can display the state of the park switch.

OPEN is displayed when the gear shift lever is not in PARK.

CLOSED is displayed when the following conditions exist:

Refer to Steering Wheel and Column for more information on the park switch.

The speedometer is an analog gauge that is located in the instrument cluster. The VCM/PCM sends vehicle speed pulses to the instrument cluster on a designated circuit.

The speedometer system consists of the instrument cluster, vehicle speed sensor (VSS), PCM/VCM and related wiring. Repairs to the instrument cluster can only be performed by an authorized instrument cluster service center.

The PCM/VCM converts the analog output from the vehicle speed sensor to a digital signal containing 4,000 pulses per mile (PPM) for the instrument cluster. The PCM/VCM is matched to the final drive and tire size of each vehicle. If the final drive or tire size is changed for any reason, the PCM/VCM must be updated in order to match the new final drive or tire size. If not, the signal will not be accurate for proper speedometer/odometer operation. An incorrect signal can affect the antilock brakes and the cruise control systems.

The VSS is a permanent magnet signal generator that sends an analog signal proportional to the propeller shaft speed to the PCM/VCM. The VSS mounts to the transmission tailshaft extension housing on 2-wheel drive models and the transfer case output shaft housing on 4-wheel drive models.

The tachometer is an analog gauge that is located in the instrument cluster. The VCM/PCM sends tach pulses to the instrument cluster on a dedicated circuit at the rate of 2 pulses per engine revolution when the engine is running. The instrument cluster will then interpret the tach pulses in order to appropriately display engine RPM on the tachometer.

The transmission temperature gauge is an analog device that is located in the instrument cluster. The VCM/PCM uses class 2 serial data communications in order to inform the instrument cluster of the transmission temperature. The instrument cluster operates the transmission temperature gauge in order to appropriately display the transmission temperature. The transmission temperature gauge displays temperatures of 100°F, 200°F, and 300°F.

The voltmeter is an analog gauge located in the instrument cluster. The voltmeter measures battery voltage when the ignition switch is in the RUN or START positions. The voltmeter displays the electrical system voltage. When the engine is running, the indicator should be between 10 and 16 volts.

The voltmeter has a red band at each extreme end of its range. It is normal operation for the indicator to rest just outside of either band. If the indicator rests inside either band, a charging system problem is indicated.