EGR Electronic Vacuum Regulator Solenoid: Description and Operation

EGR Control Solenoid Circuit:

NOTE: Because different models and engine applications vary in wire colors, circuit numbers, and pin numbers, the above image is a typical example. Refer to COMPUTERS AND CONTROL SYSTEMS/SCHEMATIC AND ROUTING DIAGRAMS for specific schematic applications.

OPERATION:
To regulate EGR flow, the control module operates a solenoid to control the EGR valve. This solenoid is normally closed. By providing a ground path, the control module energizes the solenoid which then allows vacuum to pass to the EGR valve.

The control module monitors EGR effectiveness by de-energizing the EGR control solenoid, which prevents vacuum flow to the EGR valve. With the EGR valve closed and oxygen sensor cycling normally, fuel integrator counts will be greater than they were during normal EGR operation. If the change is not within the calibrated window, a Code 32 will be set.

The control module will check EGR operation when:

- Engine speed is above 2000 rpm.
- Engine vacuum is between 8 and 30 kPa.
- No change in throttle position while test is being run.