Neutral Safety Switch: Description and Operation

This contact type switch detects whether the select lever is in the PARK or NEUTRAL position, and is mounted on the transmission. Based on this information, the Control Unit is able to sense the automatic transmission's load and operates the Idle Speed Control (ISC) servo accordingly.
The Inhibitor Switch also acts a safety switch. If the gear select is in REVERSE or a DRIVE gear, the vehicle will not start.