Instrument Cluster

INSTRUMENT CLUSTER

The instrument cluster consists of the following components:

Instrument Cluster Component Locations:

PRINCIPLES OF OPERATION

Speedometer/Odometer
The instrument cluster receives vehicle speed information from the powertrain control module (PCM) via the standard corporate protocol (SCP) network. On vehicles equipped with gasoline engines, the PCM receives its signal from the output shaft speed sensor (OSS). On vehicles equipped with diesel engines, the PCM receives its signal from the vehicle speed sensor (VSS).

The SELECT/RESET button has three functions. First, pressing the SELECT/RESET button will toggle between the odometer and trip odometer settings. When the trip odometer is displayed, pressing and holding the SELECT/RESET button will reset the trip odometer. There are two trip odometers available: A and B. Pressing the SELECT/RESET button while in trip odometer will toggle between trip odometer A and trip odometer B. Lastly, the instrument cluster self-test is entered by pressing and holding the SELECT/RESET button down with the key in the OFF position, then turning the key to RUN.

The instrument cluster receives odometer rolling count status from the PCM and stores the mileage in non-volatile memory (NVM). When the instrument cluster fails to receive the odometer rolling count status for more than two seconds, the odometer display will show dashes.

Tachometer
The instrument cluster receives tachometer information from the PCM via the SCP network.

Fuel Gauge and Low Fuel Warning Indicator
The fuel level sender is hardwired to the instrument cluster. The instrument cluster sends a signal voltage to the fuel level sender, which contains a variable resistor. The instrument cluster uses the return voltage to determine fuel level. When the fuel gauge reads approximately 1/8th tank, the instrument cluster illuminates the low fuel warning indicator.

Battery Voltage Meter and Charging System Warning Indicator
The instrument cluster detects system voltage either directly from the generator (single generator system). When the system voltage is too low, the instrument cluster activates the charging system warning indicator.

Oil Pressure Gauge
The instrument cluster sends a signal voltage to the normally open oil pressure switch. When low oil pressure is detected, the switch closes, grounding the circuit and causing the oil pressure gauge to display low pressure.

Engine Coolant Temperature Gauge
The instrument cluster receives information on the engine coolant temperature from the PCM via the SCP network. When the engine coolant temperature is within normal operating range, the gauge needle will be in the normal range (between "H" and "C").

Safety Belt Warning Indicator
The driver safety belt switch is hardwired to the instrument cluster. When the safety belt is engaged, the driver safety belt switch grounds the circuit, causing the lamp to turn off. When the safety belt is unbuckled, the ground is removed and the instrument cluster illuminates the safety belt warning indicator.

Brake Warning Indicator
The brake warning indicator receives its ground signals from the following sources:
- The parking brake switch provides a ground when the parking brake is engaged.
- The brake fluid level switch provides a ground when the brake fluid level is low.
- The low vacuum switch (diesel only) senses low engine vacuum and provides a ground.

The ignition switch provides the brake warning indicator prove-out by supplying a ground when it is in the START position.

Anti-Lock Brake System (ABS) Warning Indicator
The instrument cluster receives status information from the ABS module through a hardwired circuit from the ABS module. When the ABS module detects a fault, it grounds the circuit, causing the ABS warning indicator to illuminate.

Air Bag Warning Indicator
The air bag warning indicator circuit is grounded by the restraint control module (RCM), through a hardwired circuit, when the RCM detects a fault in the air bag system. Failure of the air bag warning indicator to prove out once the key is turned to the RUN position indicates a fault in the air bag system.

Service Engine Soon Warning Indicator
When there is a fault in the engine control system, the PCM sends a message via the SCP network to the instrument cluster, causing the service engine soon warning indicator to illuminate.

Fuel Filler Cap Loose Warning Indicator (if equipped)
When the PCM detects that there is a leak in the evaporative emissions (EVAP) system that could be the result of a loose fuel filler cap, the PCM sends a message via the SCP network to the instrument cluster, causing the fuel filler cap loose warning indicator to illuminate.

High Beam Indicator
The high beam indicator will illuminate when the multifunction switch is in the high beam position and sends a battery signal to the instrument cluster.

Right and Left Turn Indicator
The right and left turn indicators will illuminate when the multifunction switch is in either turn signal position or hazard lamps position and sends a battery signal to the instrument cluster.

Wait to Start Indicator (Diesel Only)
The PCM provides the ground for the wait to start indicator. The glow plugs and the wait to start indicator operate at the same time. The light illuminates until the PCM has provided time for the glow plugs to heat the combustion chamber. The PCM then opens the indicator ground circuit, turning off the indicator lamp. The wait to start indicator prove-out is in the RUN position and is controlled by the PCM.

Water in Fuel Indicator (Diesel Only)
The water in fuel indicator receives a ground signal when water is sensed in the fuel. The PCM provides the ground for the water in fuel warning indicator. The water in fuel indicator prove-out is in the RUN position and is controlled by the PCM.

Engine Air Filter Warning Indicator (Diesel Only)
When the engine air filter sensor detects that a new air filter needs to be installed, it grounds a signal from the PCM. The PCM then sends a signal to the instrument cluster via the SCP communications network to activate the engine air filter warning indicator.