Engine Oil Information Function

Engine Oil Information Function




Shown on ENGINE 112
A1 Instrument cluster
B40 Oil sensor (oil level, temperature and quality)
N3/10 Motor electronics control unit
CAN Data bus




Signal assignment oil sensor
1 On/off ratio signals Okay
A Oil temperature 20 to 80%
B Oil level 20 to 80%
C Oil quality 20 to 80%
2 On/off ratio signals >80 %
A Oil temperature > +160 °C
B Oil level >80 mm
C Oil quality good
3 On/off ratio signals <20 %
A Oil temperature < -40 °C
B Oil level <0 mm
C Oil quality poor
T pulse duty factor 100 %

Task
- The display in the instrument cluster warns the driver that the oil level is too low
- Detecting oil temperature
- Detecting oil quality for demand-based oil change interval display

Design/function
The oil level, oil temperature and oil quality arer detected by means of an oil sensor installed in the oil pan. The sensor operates in accordance with the capacitive measuring principle and features integrated electronics which analyze the three signals.

The information is continuously transmitted via a PWM signal to the engine control unit and communicated via the CAN to the instrument cluster. Each information block consists of three successive square-wave signals, followed by a short pause. This is followed by a short pause. A measured variable is assigned to each square-wave signal (A, B, C). The quantisizing in each case is based on the on/off ratio of approx. 19 to 81%.

The oil quality is detected for the demand-based oil change interval display. The oil quality is detected on the basis of the capacitance of the engine oil (dielectric), this being as much as 6 times greater if the oil quality is poor. The measuring range for the oil level is 80 mm (normal level ±40 mm), accuracy of measurement approx. ±3 mm.

Oil level and oil quality (capacitance of the engine oil) are independent of each other. The information is not compensated until it reaches the engine control unit before being transmitted to the CAN.

Faults at the oil sensor are detected by the engine control unit and entered in the fault memory.

The voltage for the oil sensor (approx. 5 V) is supplied by the engine control unit.