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 (ECT)
on the analog ECT gage as determined by the engine control module (ECM). The ECM 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 indicating
the engine coolant temperature. The engine coolant temperature gage defaults to 75°C
(160°F) or below when the following conditions occur:
| • | The ECM detects a malfunction in the engine coolant temperature sensor
signal circuit. |
| • | The IPC detects a loss of class 2 communications with the ECM. |
For additional information on the engine cooling system, refer to
Cooling System Description and Operation
in Engine Cooling.
Engine Oil Pressure (EOP) Gage
The instrument panel cluster (IPC) displays the engine oil pressure (EOP) on
the analog EOP gage as determined by the engine control module (ECM). The ECM 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 indicating
the engine oil pressure. 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. |
Fuel Gage
The instrument panel cluster (IPC) displays the fuel level on the analog fuel
gage as determined by the engine control module (ECM). The ECM 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 indicating
the filtered fuel level percent. The ECM 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. |
For additional information on the fuel system refer to
Fuel System Description
in Engine Controls - 7.8L.
Hourmeter
The instrument panel cluster (IPC) displays the accumulated engine run time
hours using the reconfigurable odometer 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 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). 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). The IPC receives a class 2 message
indicating the gear position. The PRNDL display blanks if:
| • | The TCM 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. |
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).
The ECM 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 in order to calculate
the vehicle speed.
The IPC also receives a class 2 message from the ECM indicating the vehicle
speed. The IPC compares the class 2 value to the vehicle speed signal from
the ECM 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 to indicate the vehicle speed. Refer to
Diagnostic System Check - Vehicle
in Vehicle DTC Information.
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). The IPC uses
the engine speed signal circuit--2 pulses/engine revolution--from
the ECM in order to calculate the engine speed.
The IPC also receives a class 2 message from the ECM indicating the engine
speed. The IPC compares the class 2 value to the engine speed signal from
the ECM 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 to indicate the engine speed. Refer to
Diagnostic System Check - Vehicle
in Vehicle DTC Information.
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). The IPC receives a class 2
message from the ECM indicating the electrical system voltage. The volt gage defaults
to 9 volts when the IPC detects a loss of communications with the ECM. For
additional information on the engine electrical system, refer to
Charging System Description and Operation
in Engine Electrical.
