Oil Level Sensor For ECM: Description and Operation

GF18.40-D-2000H Component Description of Oil Sensor








Location

Shown with engine 642

B40 Engine oil sensor





Shown with engine 646

B40/5 Engine oil sensor





Shown with engine 651

B40/6 Engine oil level sensor

The engine oil sensor or the engine oil level sensor with integrated engine oil temperature sensor (B40/9), with engine 651, is located on the oil pan.

Task

^ To warn the driver through a display in the instrument cluster (A1) that the oil level is too high or too low.
^ Detecting the oil temperature.
^ To detect the oil quality for an oil change interval display according to demand.

Function

An engine oil sensor or engine oil level sensor with integrated engine oil temperature sensor installed in the oil pan enable the oil level, oil temperature and oil quality to be recorded. The sensor operates in accordance with the capacitive measuring principle Task and features integrated electronics which analyze the three signals. Information is constantly provided through a pulse width modulation (PWM) signal to one of the following engine control units:

- CDI control unit (N3/20), with engine 642
- CDI control unit (N3/21), with engine 646
- CDI control unit (N3/28), with engine 651

The CDI control unit sends the corresponding information as messages "T_OIL (oil temperature)", "OIL_LE (oil level)" and "OIL_QUAL (oil quality)" through the Controller Area Network bus Class C (engine compartment) (CAN-C) to the instrument cluster.

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.

Establishment of the size in each case is based on the duty cycle of approx. 20 to 80%.

The oil quality is measured 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; the precision of the measurement about 3 mm. oil level and oil quality (capacitance of the engine oil) are dependent on each other. The information is first calculated in the CDI control unit before being transmitted via the CAN-C. Fault on engine oil sensor or engine oil level sensor with integrated engine oil temperature sensor are detected by the CDI control unit and entered into the fault memory. The power supply (approx. 5 V) for the engine oil sensor or engine oil level sensor with integrated engine oil temperature sensor is provided by the CDI control unit.