MIL Operation
The powertrain control module (PCM) controlled lamps are intended to
alert the driver to an operating condition which may require immediate attention.
Ignition positive voltage powers the PCM controlled lamps. The PCM commands
the lamps ON by applying ground to the lamp control circuit.
The malfunction indicator lamp (MIL) is located on the instrument panel,
CHECK ENGINE or SERVICE ENGINE SOON. The MIL performs the following functions:
| • | It informs the driver that a problem has occurred and that the
vehicle should be taken for service as soon as possible. |
| • | As a bulb check and system check, the MIL will illuminate with
the ignition ON and the engine not running. When the engine is started,
the MIL will turn OFF. If the MIL remains ON, the Self-Diagnostic System
has detected a problem. If the problem goes away, the MIL will turn OFF
in most cases, but a diagnostic trouble code will remain stored. |
| • | If the MIL is illuminated, then the engine stalls, the MIL will
remain Illuminated so long as the ignition is ON. |
| • | If the MIL is not illuminated and the engine stalls, the MIL will
not illuminate until the ignition is cycled OFF, then ON. |
Perform the Powertrain On Board Diagnostic (OBD) System Check first,
when the following conditions are present:
| • | The MIL does not turn ON when the ignition is turned to the RUN
position |
| • | The MIL remains ON while the engine is running |
| • | When you suspect a driveability problem |
| • | When you suspect an emissions problem |
Low Oil Level Lamp
The PCM commands the low oil level lamp ON if the engine oil level sensor
indicates that a low oil level condition exists. The PCM determines whether
or not to test for low oil level based on the difference between engine
coolant temperature at the last shutdown and engine coolant temperature
at start-up. This is to ensure that the oil has drained back into the oil
pan before testing.
The engine oil level switch is a simple float switch that is grounded
when the engine oil level is OK. When the ignition is first turned ON, the
PCM commands the low oil level lamp ON for a brief period of time to test
the bulb, approximately 3 seconds. The PCM also checks the engine
oil level switch circuit at start-up. If the engine has been running, the
PCM performs a test routine based on engine coolant temperature to ensure
that the engine oil drained back into the sump before checking the state
of the engine oil level switch. If the engine coolant temperature is between
15°C-130°C (59°F-266°F), the PCM compares the
engine coolant temperature at the last key OFF to the engine coolant temperature
at the current key ON. If the difference between the recorded temperature
values is at least 12°C (54°F), the PCM will test the engine oil
level.
Hot Lamp
The PCM commands the hot lamp ON when the engine coolant temperature
exceeds 124°C (255°F). The PCM commands the hot lamp OFF when the
engine coolant temperature falls below 121°C (248°F).
Generator Lamp
The PCM commands the generator lamp ON under the following conditions:
| • | When the engine speed is more than 1200 RPM and system
voltage falls below 10 volts for longer than 10 seconds. The
PCM commands the generator lamp OFF when system voltage rises to above
12 volts. |
| • | When the generator control circuit (L terminal) remains low for
longer than 10 seconds. |
| • | When the engine speed is between 1000-1300 RPM and the generator's
F terminal duty cycle is more than 95 percent for 60 seconds. |
| • | When the engine speed is between 1000-1300 RPM and the generator's
F terminal duty cycle is less than 5 percent for 30 seconds. |
Change Oil Lamp
The PCM commands the oil life monitor lamp ON when an oil change is
required. The PCM calculates remaining oil life based on total engine revolutions
and calculated engine oil temperature for each start-up since the oil life
monitor was reset.
