Gear Position Sensor (Manual Transmission Only)
The transfer box control module uses positional information from the manual gear position sensor to determine which gear the transmission is in. This information is broadcast on the CAN bus for display on the instrument cluster and for use by other vehicle systems. Vehicles fitted with automatic transmission use a similar message broadcast by the Transmission Control Module (TCM). Vehicles fitted with manual transmission have a learning function, which compares the positional information from the sensor with the gear ratio calculated from the ratio of engine speed to transmission output shaft speed. The transmission learning is carried out at end of manufacture. If a new transmission is fitted during the life of the vehicle the learning algorithm needs to learn the characteristics of the new transmission.
The instrument cluster displays the selected gear as determined by the transfer box. The transfer box also uses this to check the vehicle is in neutral before attempting a range change.