Ignition switch (ST) and the band switch (TR) in vehicles with automatic transmission
After turning the ignition key to the START position the battery voltage is applied to the switch range (TR) and from there to the engine control unit.
If the selector lever is not in position P or N, battery voltage is supplied to the control unit. On the basis of this signal, the control unit determines the mode of operation of an automatic transmission and maintains the speed of the crankshaft of the engine at an optimal level.