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 air bag indicator flashes for 7 seconds. |
| • | The air brakes indicator illuminates briefly. |
| • | The ABS indicator illuminates briefly. |
| • | The brake indicator illuminates briefly |
| • | The charge indicator illuminates briefly. |
| • | The change engine oil indicator illuminates briefly. |
| • | The check gages indicator illuminates briefly. |
| • | The engine overspeed indicator illuminates briefly. |
| • | The engine shutdown indicator illuminates briefly. |
| • | The fasten seat belt indicator illuminates for about 8 seconds. |
| • | The low coolant indicator illuminates briefly. |
| • | The low engine oil level indicator illuminates briefly. |
| • | The reduced engine power indicator illuminates briefly. |
| • | The service engine soon indicator illuminates continuously. |
| • | The PRNDL and the odometer segments illuminate. |
Indicators and Warning Messages
Refer to
Indicator/Warning Message Description and Operation.
Engine Coolant Temperature (ECT) Gage
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:
| • | The ECM/PCM detects a malfunction in the engine coolant temperature sensor signal circuit. |
| • | The IPC detects a loss of class 2 communications with the ECM/PCM. |
For additional information on the engine cooling system, refer to
Cooling System Description and Operation.
Engine Oil Pressure (EOP) Gage
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 IPC detects a loss of class 2 communication with the ECM/PCM. |
Fuel Gage
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:
| • | The IPC detects a loss of class 2 communications with the ECM/PCM. |
Hourmeter
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.
Odometer
The vehicle odometer is calculated and stored electronically in the instrument panel cluster (IPC). The 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.
PRNDL Display
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 TCM (LB7, LLY and LG4) or the ECM/PCM (L18) detects a malfunction in the transmission range switch circuit. |
| • | The transmission range displayed does not correspond with the PRNDL class 2 message received by the IPC. |
| • | The IPC detects a loss of class 2 communications with the TCM or the ECM/PCM. |
Speedometer
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.
Tachometer
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.
Transmission Temperature Gage
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.
Volt Gage
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.
