Exhaust Gas Recirculation (EGR) Control

Fig. 37 EGR Solenoid Control System:

CIRCUIT OPERATION
The EGR control system is used to allow precise control of the EGR valve.
When conditions are NOT suitable for EGR operation, based on signals sent via the crank angle sensor, air flow meter, engine temperature sensor and the ignition switch, the ECU energizes the solenoid. Refer to EMISSION CONTROLS for further description of the EGR valve.

Fig. 144 Vacuum Solenoid:

EGR CONTROL SOLENOID
The ECU supplies the ground circuit to the solenoid. This energizes the solenoid, redirecting vacuum from the source port and valve port to the source port and vent port preventing EGR operation.
The EGR system does not operate under the following conditions:
1. Engine starting.
2. Engine speed over 2700 RPM.
3. Low coolant temperature.
4. High coolant temperature.