MIL Operation
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 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, then the engine stalls, the MIL will
remain Illuminated so long as the ignition switch is ON. |
| • | Now, if the MIL is not
illuminated and
the engine stalls, the MIL will not illuminate until the ignition switch is
cycled OFF, then ON. |
Perform the Powertrain On-Board Diagnostic System Check first, when
the following conditions are present:
| • | When the MIL does not turn ON when the 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 |
The 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.
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 startup.
This is to ensure that the oil has drained back into the oil pan before testing.
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 120°C (248°F).
Change Oil Lamp
The PCM commands the Oil Life Monitor lamp ON when an oil change is
require. The PCM calculates remaining Oil life based on total engine revolutions
and calculated engine oil temperature for each startup since the Oil Life
monitor was reset.
Generator Lamp
The PCM commands the generator lamp ON under the following conditions:
| • | When the engine speed is greater 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 below 2000 rpm and the generator
feedback circuit (F terminal) duty cycle falls below 5% and remains below
15% for longer than 20 seconds. |
| • | When the engine speed is above 4000 rpm and the generator
feedback circuit (F terminal) duty cycle increases to above 95% and remains
above 85% for longer than 20 seconds. |
Engine Oil Level Sensor
Engine oil level is determined by an optical sensor which detects oil
level immediately upon powerup. While the engine oil level sensor is determining
oil level, the sensor holds the state of the engine oil level PCM input circuit
at ignition voltage. The amount of time the engine oil level sensor requires
to determine oil level is about 1.5 seconds. After the engine oil level has
been determined, the engine oil level sensor will ground the engine oil level
PCM input circuit for 1 to 2 seconds if oil level is OK or 6 to 10 seconds
if oil level is low. The PCM determines oil level based on the engine oil
level PCM input signal duration. The PCM also monitors the engine oil level
PCM input signal to determine whether the engine oil level PCM input circuit
is open or shorted.
