Oil sensor function - GF18.40-P-4111-02AM

Oil sensor signal assignment 

The oil sensor operates in accordance with the capacitive measuring principle and features integrated electronics which analyze the three signals (oil level, temperature and quality).

The information is sent constantly in the form of a pulse width modulated signal (PWM signal) to the ME control unit (N3/10) and then via the CAN data bus to the instrument cluster (A1).

Each information block consists of three successive square-wave signals, 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 (T) of approx. 20 to 80%.

Power for the oil sensor (approx. 5 V) is supplied by the ME control unit.

Oil level and oil quality are detected on the basis of the capacitance of the engine oil (dielectric).

The capacitance of the engine oil is 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) for a measuring accuracy of about ca. ±3 mm.

The oil temperature is detected by the integrated temperature sensor.

All the signals are processed in the integrated electronics in the oil sensor to form a PWM signal and passed on to the ME-SFI [ME] control unit.

Oil level and oil quality (capacitance of the engine oil) are interdependent. For this reason this information is not compensated until it reaches the ME control unit before being transmitted via CAN data bus.

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