Throttle Opener Control System

When vehicle is first started, ECM activates a Throttle Opener Solenoid Vacuum (TOSV) valve, which supplies vacuum to the throttle opener. The ECM controls TOSV valve according to ignition signal, starter signal and signal from Engine Coolant Temperature (ECT) sensor. The TOSV valve is activated for .2-35 seconds after engine starts, depending on ECT sensor.

Energizing the TOSV valve opens a vacuum passage between TOSV valve filter and throttle opener, and closes the manifold vacuum passage. When vacuum passage is closed, diaphragm spring pushes on throttle linkage, increasing throttle opening.

Once vehicle starts, ECM de-energizes the TOSV valve, allowing manifold vacuum to pass through TOSV valve to throttle opener diaphragm. Diaphragm will retract, allowing throttle linkage to return to normal base idle position.