Transmission Position Sensor/Switch: Description and Operation

TRANSMISSION RANGE SWITCH, GEAR ENGAGED
The Transmission Range (TR) switch is fitted on the transmission housing. It contains the reversing light switch, starting interlock contact and switches which inform the Transmission Control Module (TCM) about which range (gear) the transmission is operating in.





In principle, the TR switch is a position switch which is powered via +X and in which a number of slip contacts indicate the position. The combination of terminals A, B, C and D gives the selector lever position (see table above). The slip contacts can be either closed (=ON) or open (=OFF).





TRANSMISSION RANGE SWITCH - REVERSING LIGHT CONTACT
Contact function 31 pins 1 and 2 is used to control the reversing light.

When gear position R is selected, the contact is closed and there is power to the reversing light lamps. In other gear positions the contact is open.

In markets with side reversing lights this contact controls the reversing light relay (405), which feeds power to all reversing light lamps.





STARTING INTERLOCK CONTACT
Contact function 77 pin 5/7 is used to control the starting relay.

Contact pin 7 is powered via fuse 36 with battery positive voltage. In cars with an anti-theft alarm the power supply comes via this alarm control module. In the P and N positions contact function 77 is closed and the battery positive voltage is fed to the starting relay.

In all other gear positions the contact function is open, i.e. the starting relay receives no voltage.