Neutral Sensor
MSA Test Module 'Zero Gear Sensor'
Automatic engine start-stop, zero gear sensor:
On vehicles with manual transmission, the zero gear sensor is fitted on the transmission case. The zero gear sensor is a PLCD sensor, which means the sensor detects a linear change in the location (excursion) without contact on the basis of position changes with regard to the magnetic state. The gearshift operation shifts the selector rod (4) and thus the magnet in the transmission. The PLCD sensor enables the engine management system to detect the position of the gear stick.The following illustrations show the schema of the assembly and sectional views of the sensor attached to the transmission:
The following part designations apply:
- 1: Motor control
- 2: PLCD sensor
- 3: Permanent magnet
- 4: Selector rod
From a practical point of view, the transmission zero gear sensor is divided into two components (2) and (3). The smaller component, the permanent magnet, is located inside the transmission.
So that the engine management system knows the zero position of the gear selector switch / gear stick, it is necessary to be able to learn this position in the vehicle. This learning routine takes place for the most part automatically in the plants and is possible using the DIS tester in cases of repair. To run this, run the service function
The zero position of the gear stick is normally approx. 50 % (+/- tolerance).
When checking the correct function of the sensor within the framework of this test module, there is also a check of the tendency for the signal value to change on pushing the gear stick in the 'on' direction. Depending on the shift direction of the gear stick, the result is a rising or falling tendency of the returned position value.
NOTE: Incorrectly learned values of the zero position lead to problems with regard to the availability of the automatic engine start-stop function and deficiencies with regard to reproducibility of the system characteristics of all MSA-specific parameters.