Throttle Positioner System: Description

The throttle positioner (TP) system controls exhaust emissions during deceleration by holding the throttle plate at an above-idle position during off-throttle operation. This prevents the fuel mixture from being starved of air and helps control HC and CO emissions. The controlling unit is a throttle positioner diaphragm which is vacuum operated.

The system consists of a throttle positioner diaphragm, a vacuum transmitting valve (VTV) on Corolla and Tercel models, a bimetal vacuum switching valve (BVSV) and jet restrictor on Starlet models, and a thermostatic vacuum switching valve (TVSV) on Tercel models.