Transmission Position Sensor/Switch: Description and Operation

IGNITION SWITCH - ST AND TRANSAXLE RANGE(TR) SWITCH [A/T]
When the ignition switch is set to the ST position, battery voltage is applied through the ignition switch and transaxle range switch to the ECM.
If the selector lever is not in the P or N position, battery voltage will not reach the ECM.
Based on this signal, the ECM determines the automatic transaxle load and drives the ISC motor to maintain optimum idle speed.