WL-C Engine Emission System
EGR Solenoid Valve
BT-50_01047
A To EGR valve 1 EGR solenoid valve
B To vacuum chamber
EGR Control
• The PCM controls the position of the EGR valve by means of the EGR solenoid valve
(via duty signal) and the EGR control solenoid valve (via ON/OFF signal).
– When EGR is desired the PCM controls the EGR solenoid valve with a large duty
ratio and energizes the EGR control solenoid valve, so that vacuum is applied to the
EGR vacuum actuator. Due to this the EGR valve opens and exhaust gas is
recirculated.
– When less or no EGR is desired the PCM controls the EGR solenoid valve with a
small duty ratio and energizes the EGR control solenoid valve, so that the vacuum
applied to the EGR vacuum actuator is reduced by a ventilation passage. Due to this
the spring-loaded EGR valve closes and less or no exhaust gas is recirculated.
– When the EGR should be cut off (e.g. during acceleration) the PCM de-energizes the
EGR control solenoid valve, so that the EGR vacuum actuator is ventilated
irrespective of the control by the EGR solenoid valve. Due to this the EGR valve
closes quickly and EGR is stopped.
Service Training BT-50 01-37
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