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.
