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:

Refer to Indicator/Warning Message Description and Operation .

The instrument panel cluster (IPC) displays the engine coolant temperature on the analog engine coolant temperature (ECT) gage as determined by the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM monitors the signal circuit of the ECT sensor. When the sensor resistance is high, the engine coolant temperature is low. When the sensor resistance is low, the engine coolant temperature is high. The IPC receives a class 2 message from the ECM/PCM indicating the engine coolant temperature. The ECT gage defaults to 75°C (160°F) or below when the following conditions occur:

For additional information on the engine cooling system, refer to Cooling System Description and Operation .

The instrument panel cluster (IPC) displays the engine oil pressure on the analog engine oil pressure (EOP) gage as determined by the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM monitors the signal circuit of the EOP sensor. When the EOP sensor resistance is high, the engine oil pressure is high. When the EOP sensor resistance is low, the engine oil pressure is low. The IPC receives a class 2 message from the ECM/PCM indicating the EOP. The EOP gage defaults to 0 kPa (0 psi) when the following conditions occur:

The instrument panel cluster (IPC) displays the fuel level on the analog fuel gage as determined by the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM monitors the signal circuit of the fuel level sensor. When the fuel level sensor resistance is high, the fuel gage indicates full. When the fuel level sensor resistance is low, the fuel gage indicates empty. The IPC receives a class 2 message from the ECM/PCM indicating the filtered fuel level percent. The ECM/PCM uses 2 filters for the fuel level percent. The slow filter is used during normal operation. The fast filter is used when the engine is just started or when the vehicle is in Park or Neutral. The fast filter allows the fuel gage to reach the current fuel level quickly. The fuel gage defaults to empty when the following conditions occur:

For additional information on the fuel system refer to the following:

The instrument panel cluster (IPC) displays the accumulated engine run time hours using the reconfigurable odometer vacuum fluorescent (VF) display. The engine run time hours displays only when the ignition is in the OFF or ACC position and the trip reset switch is pressed for approximately 4 seconds. When the ignition is in the OFF or ACC the IPC displays the engine accumulated hours for up to 30 seconds. The value of the accumulated hours does not change when the battery is disconnected. The hourmeter resets to 0.0 when 10,000 hours are accumulated. The IPC then begins to reaccumulate the engine run time hours from 0.0 hours.

The instrument panel cluster (IPC) contains a season odometer and a trip odometer. Momentarily press the trip/reset switch on the IPC in order to toggle between the season odometer and the trip odometer. Press the trip/reset switch for greater than 2 seconds, while the trip odometer is displayed, in order to reset the trip odometer. The IPC calculates the mileage for the odometer based on the vehicle speed signal circuit from the engine control module (ECM)/powertrain control module (PCM). The odometer will display 'error' if an internal IPC memory failure is detected.

The instrument panel cluster (IPC) displays the selected gear position as determined by the transmission control module (TCM) (LB7, LLY and LG4) or the engine control module (ECM)/powertrain control module (PCM) (L18). The IPC receives a class 2 message indicating the gear position. The PRNDL display blanks if:

The instrument panel cluster (IPC) displays the vehicle speed on the analog speedometer based on the vehicle speed signal from the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM converts the data from the vehicle speed sensor to a 4,000 pulses/mile signal. The IPC uses the vehicle speed signal circuit from the ECM/PCM in order to calculate the vehicle speed.

The IPC also receives a class 2 message from the ECM/PCM indicating the vehicle speed. The IPC compares the class 2 value to the vehicle speed signal from the ECM/PCM to determine if the vehicle speed is valid. When the IPC detects a malfunction in the vehicle speed signal circuit, the IPC uses the class 2 message from the ECM/PCM to indicate the vehicle speed. Refer to Diagnostic System Check - Vehicle .

The instrument panel cluster (IPC) displays the engine speed on the analog tachometer based on the engine speed signal from the engine control module (ECM)/powertrain control module (PCM). The IPC uses the engine speed signal circuit -- 2 pulses/engine revolution -- from the ECM/PCM in order to calculate the engine speed.

The IPC also receives a class 2 message from the PCM indicating the engine speed. The IPC compares the class 2 value to the engine speed signal from the ECM/PCM to determine if the engine speed is valid. When the IPC detects a malfunction in the engine speed signal circuit, the IPC uses the class 2 message from the ECM/PCM to indicate the engine speed. Refer to Diagnostic System Check - Vehicle .

The instrument panel cluster (IPC) displays the transmission temperature on the analog transmission temperature gage based on the transmission temperature gage sensor signal. The IPC monitors the signal circuit of the transmission temperature sensor in order to calculate the transmission temperature. The transmission temperature sensor signal is a variable resistance. At higher temperatures, the transmission temperature sensor has a low resistance. At lower temperatures, the transmission temperature sensor has a high resistance.

The instrument panel cluster (IPC) displays the system voltage on the analog volt gage as determined by the engine control module (ECM)/powertrain control module (PCM). The IPC receives a class 2 message from the ECM/PCM indicating the electrical system voltage. The volt gage defaults to 9 volts when the IPC detects a loss of communications with the ECM/PCM. For additional information on the engine electrical system, refer to Charging System Description and Operation .