Circuit Description

Canister purge is controlled by a solenoid valve that allows manifold vacuum to purge canister. PCM supplies a ground to energize solenoid valve (purge ON). EVAP purge solenoid control is Pulse-Width Modulated (PWM) or turned on and off several times a second. Duty cycle (pulse width) is determined by engine operating conditions including load, throttle position, coolant temperature and ambient temperature. Duty cycle is calculated by PCM and output is commanded when appropriate conditions have been met.