EGR Control Solenoid: Description and Operation

Exhaust Gas Recirculation System Circuit:

EGR AND SOLENOID 2.5L:

PURPOSE
To provide electrical control of the Exhaust Gas Recirculation (EGR) valve.

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 ECM uses RPM and information from the following sensors to regulate the EGR solenoid:
- Engine Coolant Temperature (ECT) sensor - above 25°C.
- Throttle Position (TP) sensor - off idle.
- Manifold Absolute Pressure (MAP) sensor

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:
- Vehicle speed is above 35 mph.
- Engine vacuum is between 20 and 55 kPa.
- No change in throttle position greater than 2% while test is being run.
- TP angle between 5% and 40%.
- Short term fuel trim change <10 counts.
- Test conditions must fail for three consecutive times.