Transmission Position Sensor/Switch: Description and Operation

PURPOSE / OPERATION
The Park/Neutral Position (PNP) switch goes on when the shift lever is in the "N" or "P" shift position. When it goes on the terminal "NSW" of the ECM is grounded to body ground via the starter relay and theft deterrent ECU, thus the terminal "NSW" voltage becomes 0.0 volts. When the shift lever is in the "D", "2", "L" or "R" position, the ECM switch goes off, so the voltage of ECM terminal "NSW" becomes battery voltage, the voltage of the ECM internal power source.
If the shift lever is moved from the "N" position to the "D" position, this signal is used for air-fuel ratio correction and for idle speed control (estimated control), etc.