Throttle Opener Control System

When vehicle is first started, ECM energizes throttle opener Vacuum Switching Valve (VSV). This blocks manifold vacuum which normally draws throttle opener diaphragm and linkage rod to base idle position.

Once vehicle is started, ECM will de-energize VSV. This allows manifold vacuum to pass through VSV to throttle opener diaphragm. Diaphragm will then retract, allowing throttle linkage to return to normal base idle position.