PCM Controlled Lamps
The PCM controlled lamps are intended to alert the driver to an operating condition which may require immediate attention.
The Engine Oil Level Switch is used to detect low engine oil level conditions.
Operation
The indicator lamp(s) are powered from an ignition 1 feed fuse. The PCM controls the lamp(s) by supplying ground. The PCM controlled lamps operate as follows:
| • | Generator Lamp : The PCM supplies battery voltage to the generator's internal regulator. When a fault in the Charging System occurs, the internal regulator grounds the L terminal voltage. The PCM recognizes the fault condition and illuminates the Generator Lamp. |
| • | Low Oil Level Lamp : The PCM commands the Low Oil Level Lamp ON if the engine oil level switch 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. |
Engine Oil Level Switch
The Engine Oil Level Switch is a simple float switch that is grounded when the engine oil level is OK. The PCM checks the Engine Oil Level switch circuit at startup. Before checking the state of the Engine Oil Level switch, the PCM performs a test routine based on time and engine coolant temperature to ensure that the engine oil has drained back into the sump. To test for low oil level at startup, one of the following conditions must be present:
| • | If the engine coolant temperature was between 15°C (59°F) and 140°C (284°F) at the last key OFF, the engine coolant temperature at key ON must be at least 12°C (22°F) cooler than the engine coolant temperature at the last key OFF. |
| • | If the engine coolant temperature was higher than 140°C (284°F) at the last key OFF, the time between last key OFF and the present key ON must be sufficient to allow the oil to drain back to the sump. The PCM will remain powered up for 15 seconds to ensure that the oil has drained back to the sump. If the key is turned back ON while the PCM is still powered up, the oil level will not be tested. |
The Low Oil Level Lamp will be illuminated for about a minute when the PCM checks for low oil level and the Engine Oil Level switch indicates that a low oil level condition exists (Engine Oil Level switch circuit not grounded). 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.
