MIL Operation
The PCM-controlled lamps 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:
| • | The MIL 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 switch 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 and the engine stalls, the MIL will
remain Illuminated as long as the ignition switch is ON. |
| • | If the MIL is not illuminated and the engine stalls, the MIL will
not illuminate until the ignition switch is cycled OFF, then ON. |
When the following conditions are present, perform the Powertrain On-Board
Diagnostic System Check first:
| • | When the MIL does not turn ON when the ignition switch is turned
to the RUN position |
| • | When 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 a low oil level condition. The PCM determines whether or not to
test for low oil level based on the difference between engine coolant temperature
(ECT) at the last shutdown and the ECT at startup. 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 approximately 3 seconds.
The PCM also checks the engine oil level switch circuit at startup. If the
engine has been running, the PCM performs a test routine based on the ECT
in order to ensure that the engine oil drained back into the sump before
checking the state of the engine oil level switch. If the ECT is between
15°C (59°F) and 130°C (266°F), the PCM compares the ECT
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 ECT exceeds 124°C (255°F).
The PCM commands the Hot lamp OFF when the ECT is less than 121°C (248°F).
Generator Lamp
The PCM commands the generator lamp ON during the following conditions:
| • | When the engine speed is more than 1200 RPM and system
voltage is less than 10 volts for more than 10 seconds. The
PCM commands the generator lamp OFF when system voltage rises to above 12 volts. |
| • | When the generator control circuit at the L terminal remains
low for more than 10 seconds. |
| • | When the engine speed is between 1000 RPM and 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 RPM and 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 the total engine
revolutions and the calculated engine oil temperature for each startup since
the Oil Life monitor was reset.
