Module, Oil Level: Operation
- The engine oil level is only checked by the engine switched off when the ignition key is turned to the ON position. The system exploits the ability of the oil to dissipate heat. The flow of a current inside the hot wire causes an increase in its temperature and resistance which produces a drop in voltage. If the hot wire is submerged in the oil, some of the heat is absorbed by the oil itself; therefore the values for the temperature, resistance and drop in voltage will be lower.
- With the ignition on, the oil level module sends a 210.5 mA current to the sensor hot wire. When an initial supply period has elapsed (t0 - t1 = 150 ms) the oil level module makes an initial voltage measurement (t1 - t2 = 10 ms). When a second period has elapsed (t2 - t3 = 865 ms) the oil level module makes a second measurement which is compared to the first.
- The following conditions can occur:
- 1) if difference between the two measurements is less than 125 mV, the oil level is correct;.
- 2) if it is more than 445 mV the oil is at the minimum level;
- 3) if the voltage measured during the second reading is more than 3.5 V, the sensor is broken;
- 4) if the voltage is less than 1 V, then the sensor is short circuited.
- The measurement taken is transformed into a Pulse Width Modulation (PWM) signal by the oil level module which sends it to the Powertrain Control Module (PCM). The later makes the parameter available to the Controller Area Network-Chassis (CAN-C) in order to signal the Instrument Panel Cluster (IPC).
- PWM frequency: 125 ± 10 Hz. The tolerance at ambient temperature PWM ± 3.5%. PWM signal for information on the oil level represents by duty cycle TA / TP.
- At the minimum level the PWM will be at 30% (440 mV), while at the maximum level it will be 90% (125 mV). The module is in the acquisition stage between 10% and 15%. Between 3% and 7% means that a measurement error has taken place.