Sensors

Sensor Technology

Various sensors are used for recording engine speed, temperature, pressure and distance signals:

- 4 distance sensors (combined in one housing)
- 2 speed sensors
- 2 (2WD) or 3 (4WD) pressure sensors
- 1 temperature sensor







The distance, speed and pressure sensors and the temperature sensor are connected by a wiring harness and their lines are routed outwards via the 16-pin connector. The distance and speed sensors and the temperature sensor are connected permanently to the wiring harness. The two solenoid valves and the six (2WD) or seven (4WD) pressure adjusters are connected by a second wiring harness. The wiring of this sensor is routed outwards via a 20-pin connector. The sensors are all located in the transmission. Sensors can be replaced from the outside after the oil pan and the hydraulic control unit are removed.

Speed Sensors







There are two Hall-effect sensors in each speed sensor.

Pressure Sensors







The pressure sensors for measuring the clutch pressure values are read directly at the rotary transmission feed-through point. They are installed inside the housing and are connected to the wiring harness by connectors. As the 4WD transmission has an additional clutch, the hang-on clutch, it also has an additional pressure sensor.

Temperature Sensor







The temperature sensor is used to record the sump temperature of the hydraulic oil. It is a temperature dependent resistor.

Distance Sensors







All four gearshift swinging forks have an aluminum damping element in the bottom section which dampens the signals being sent from the distance sensor. Each gearshift swinging fork is assigned a distance sensor, which converts the movement of the shift rod into a distance-proportional PWM signal.

Operating principle of the distance sensors:
The distance sensor works according to the eddy-current principle, i.e. a conductive material (a rectangular-shaped aluminium damping element on the gearshift swinging fork) drains energy from the oscillatory circuit, which leads to damping and a change in frequency in the oscillatory circuit of the sensor element. The principle is not magnetic, i.e. the gearshift swinging fork, shaped as a damping element, works as a sensor to deliver a frequency-dependent output signal depending on the overlap of the displacement sensing coil.

For every swivel arm or sensor island there is a sensing coil for measuring distance and a sensing coil for calculating the gap between the swivel arm and the printed circuit board. These sensing coils consist of a printed circuit board coil that is adapted to the geometry of the gearshift swinging fork. The position of the damping element's edge is calculated from a geometric perspective and output via the interfaces to an appropriate PWM signal. The sensor can detect two degrees of freedom (the gap between the damping element and the printed circuit board) and distance (angle of the gearshift swinging fork). The height coil is always completely covered by the damping element as it provides a frequency-proportional signal regarding the gap between the damping element and the printed circuit board.