Instrument Panel Cluster (IPC) Description and Operation

Instrument Panel Cluster (IPC) Description and Operation

Displays Test

Certain instrument panel cluster (IPC) features are tested when the ignition is turned on in order to verify the features are working properly. The following occurs at key up:

* The ABS indicator illuminates briefly.
* The service engine soon indicator (MIL) illuminates briefly.
* The charge indicator illuminates and only turns off when the vehicle is started.
* The check gauges indicator illuminates and only turns off when the vehicle is started.
* The intake heater indicator will illuminate briefly and will cycle during the engine warm-up process.

Indicators and Warning Messages

Refer to Indicator/Warning Message Description and Operation Indicator/Warning Message Description and Operation.

Engine Coolant Temperature Gage

The IPC displays the engine coolant temperature based on the information from the engine coolant temperature sensor signal circuit. A coolant temperature sensor resistance of approximately 1305 ohm will indicate a gage temperature of about 40°C (104°F) and a sensor resistance of 61.9 ohm will indicate approximately 118°C (245°F). The multifunction alarm module (MFAM) illuminates the check gages indicator when the engine coolant temperature is outside the normal operating range.

Engine Oil Pressure Gage (L18)

The IPC displays the engine oil pressure based on the information from the PCM. The oil pressure gage signal from the PCM is a variable resistance ranging from 0 - 90 ohm. A resistance of 1 ohm will display as 0 kPa (0 psi) and a resistance of 88 ohm will display as approximately 550 kPa (80 psi). The PCM illuminates the check gages indicator when the engine oil pressure is outside the normal operating range.

Engine Oil Pressure Gage (LG5)

The IPC displays the engine oil pressure based on the information from the engine oil pressure sensor signal circuit. A sensor resistance of 1 ohm will display as 0 kPa (0 psi) and a resistance of 88 ohm will display as approximately 80 psi (550 kPa). The multifunction alarm module (MFAM) illuminates the check gages indicator when the engine oil pressure is outside the normal operating range.

Fuel Gage

SINGLE TANK

The IPC displays the fuel level based on the information from the fuel level sensor signal circuit. The fuel level sensor signal is a variable resistance (0-90 ohms) based on the fuel level. When the fuel tank is full, the fuel level sensor resistance is high. When the fuel tank is empty, the fuel level sensor resistance is low.

DUAL TANK

The balance pump control module monitors the signal circuits of the primary and secondary fuel level sensors in order to determine the fuel level. When the fuel tank is full, the fuel level sensors resistance is high. When the fuel tank is empty the fuel level sensors resistance is low. Based on the fuel level sensors resistance , the balance pump control module calculates the total remaining fuel percent in the tank. The balance pump control module averages the resistance of the primary and the secondary fuel level sensors to produce a single resistance value equal to the average level of both tanks. The balance pump control module will maintain an equal fuel level for the primary and secondary fuel tanks while supplying fuel to the engine from the primary fuel tank. The IPC receives total fuel remaining information from the balance pump control module via the fuel level sensor signal circuit.

Hourmeter

The hourmeter displays the total accumulated engine run time hours. The hourmeter uses voltage pulses from the generator via the engine speed signal circuit to record vehicle engine run time hours. The accumulated hours will not change if the battery is disconnected or removed.

Odometer

The IPC contains a season odometer and a trip odometer. Briefly press the trip/reset switch on the IPC in order to toggle between the season odometer and the trip odometer. Pressing the trip/reset switch for greater than 2 seconds, while the trip odometer is displayed, will reset the trip odometer. The IPC displays the vehicle mileage and trip mileage as determined by the IPC. The IPC calculates the mileage based on the vehicle speed signal circuit. The odometer displays either miles or kilometers.

Speedometer (L18/Late LG5)

The IPC displays the vehicle speed based on the information received from the powertrain control module (PCM). The PCM converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The IPC uses the vehicle speed signal circuit from the PCM in order to calculate the vehicle speed. If a malfunction occurs in the vehicle speed signal circuit, the speedometer defaults to 0 mph (0 km/h). The speedometer displays both miles and kilometers.

Speedometer (Early LG5)

The speedometer adapter converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The IPC uses the vehicle speed signal circuit from the speedometer adapter in order to calculate the vehicle speed. If a malfunction occurs in the vehicle speed signal circuit, the speedometer defaults to 0 mph (0 km/h). The speedometer displays both miles and kilometers.

Tachometer

The PCM (L18) converts the data from the engine speed sensor to a 2 pulses/engine revolution signal. The IPC uses the engine speed signal circuit from the PCM in order to calculate the engine speed. The tachometer defaults to 0 RPM if a malfunction in the engine speed signal circuit exists.

The diesel engine (LG5) uses voltage pulses from the generator via the engine speed signal circuit to determine engine speed.

Transmission Fluid Temperature Gage

The automatic transmission fluid (ATF) temperature gage displays the transmission fluid temperature based on the information from the ATF temperature gage sensor signal circuit. The ATF temperature gage sensor resistance is used to drive the ATF temperature gage. The ATF temperature gage sensor resistance is inversely proportional to the ATF temperature. A high ATF temperature gage sensor resistance will indicate a gage temperature of approximately 40°C (104°F) and a low sensor resistance will indicate approximately 120°C (248°F).

Voltmeter

The IPC displays the system voltage as detected at the ignition 1 input of the IPC. The voltmeter measures the electrical system voltage when the ignition switch is in the RUN or START position.