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 class 2 serial data line or by a dedicated electrical circuit.

The temperature gauge is an analog device that is located in the instrument cluster. The vehicle control module (VCM) or 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 PCM/VCM determines the coolant temperature by measuring the signal voltage 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 37.8 C (100°F), 98.9 C (210°F), and 126.7 C (260°F). The CHECK GAUGES indicator will be ON if the engine coolant temperature is too high. The coolant temperature sensor (CTS) is located in the thermostat housing on the 2.2 L engine. The CTS of the 4.3 L engine is located on the left side of the cylinder head.

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 PCM/VCM. 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 PCM/VCM receives an input from the fuel level sensor. The fuel level sensor is inside of the fuel tank and has a variable resistor that is controlled by the float in the fuel tank. When the fuel tank is full and the ignition switch is in the RUN position the PCM/VCM should receive a high resistance due to the position of the float inside of the fuel tank. The PCM/VCM interprets this signal and sends a class 2 serial data message to the instrument cluster indicating the percentage of fuel in the tank. The indicator on the fuel gauge then moves to the maximum position or FULL on the gauge face. When the fuel tank is empty the float in the fuel tank is at a the lowest position and the resistance is low. The PCM/VCM interprets this signal and sends a class 2 serial data message to the instrument cluster indicating the percentage of fuel in the tank. The indicator on fuel gauge then moves to the minimum position or EMPTY on the gauge face. Corroded connections or severed ground paths generally cause the indicator to register past FULL on the gauge face. Short circuits to ground generally result in the indicator resting below EMPTY.

The fuel gauge sender assembly mounts to the top of the fuel tank and is retained by a snap ring or a cam lock. A seal is used between the fuel tank and the fuel gauge sender. The fuel gauge sender assembly consists of the following components:

The fuel gauge sender has 2 or 3 hose connections. One hose is used for the fuel feed hose. The second hose connects to the vapor canister. The third hose is used for the fuel return line to the fuel tank. Some fuel tank senders use a short connector lead. Others have the connector attach directly to the sender.

For information on fuel gauge sender replacement procedures refer to Fuel Sender Assembly Replacement in Engine Controls - 2.2 L or Fuel Sender Assembly Replacement in Engine Controls - 4.3 L.

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 to 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 kPa (0 psi) and a resistance of 88 ohms will display as 550 kPa (80 psi). 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 instrument cluster will turn ON the CHECK GAUGES indicator when the engine is running and oil pressure is too low. The oil pressure sender is located on the left side of the 2.2 L engine. The oil pressure sender is located at the top left side, near the distributor/high voltage switch for the 4.3 L engine.

The tachometer is an analog gauge that is located in the instrument cluster. The PCM/VCM sends RPM pulses to the instrument cluster on a designated circuit. These pulses may be measured in Hertz (Hz) using a digital multimeter (DMM) on the AC scale. The instrument cluster will interpret the RPM pulses in order to appropriately display the engine RPM on the tachometer.

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 10-16 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. Refer to Symptoms in Engine Electrical.

The speedometer is an analog gauge that is located in the instrument cluster. The PCM/VCM receives an analog input from the vehicle speed sensor and converts it to a digital signal containing 4,000 pulses per mile (PPM) for the instrument cluster.

The PCM/VCM sends this digital output (4,000 PPM) to the instrument cluster on a designated circuit. These pulses can be measured in Hertz (Hz) using a digital multimeter (DMM) on the AC scale. The PCM/VCM calibration 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 speedometer system consists of the instrument cluster, vehicle speed sensor (VSS), PCM/VCM and related wiring. 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 (2WD) models and the transfer case output shaft housing on 4-wheel drive (4WD) models.

Repairs to the instrument cluster can only be performed by an authorized instrument cluster service center.

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 (odometer) 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. If the vehicle battery is disconnected, the tripometer will not retain the contents.

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 purpose of illuminating the instrument cluster PRNDL display and indicator displays during the power up of the instrument cluster is to verify that all segments of the PRNDL display and that all of the indicator displays are working properly. The turn signal indicators do not turn ON during the bulb check. If an expected indicator or PRNDL segment does not function properly during the bulb check further diagnosis of the instrument cluster may be necessary. Refer to Diagnostic System Check - Instrument Cluster .