Exhaust Gas Recirculation (EGR) Control

EGR Control:

CIRCUIT OPERATION
The EGR control system is used to allow precise control of the EGR valve. The ECU receives signals from the crank angle sensor, idle switch, engine temperature sensor and the ignition switch to determine if EGR operation is warranted. The ECU supplies the ground circuit for the solenoid.

Fig. 145 Vacuum Solenoid:

EGR CONTROL SOLENOID
Only when the following conditions are met does the ECU energize the solenoid which redirects vacuum from the source port and valve port to the source port and vent port PREVENTING the EGR valve from operating:
1. Engine starting.
2. Engine speed over 2700 RPM.
3. Low coolant temperature.
4. High coolant temperature.
Refer to EMISSION CONTROLS for further description of the EGR valve.