Neutral Drive Switch (A/T)

Neutral Drive Switch:

The Neutral Drive Switch, located on the left side of the A4LD automatic transmission, functions to prevent starting the vehicle in gear and as a switch for the back-up lamps. When functioning correctly, the switch will permit engine starting only when the gear selector is in "P" or "N."

The switch also signals the ECA computer as to gear selector position.

This input is factored into ECA control calculations for outputs such as ignition timing and idle speed.