Port EGR Valve

EGR System Chart:

EGR System Circuit:

Circuit Description
The control module operates an EVRV solenoid to control the Exhaust Gas Recirculation (EGR) valve. This EVRV solenoid is normally closed. By providing a ground path, the control module energizes the EVRV solenoid which then allows vacuum to pass the EGR valve.

The control module monitors EGR effectiveness by de-energizing the EVRV solenoid, thereby, shutting "OFF" vacuum to the EGR valve diaphragm. With the EGR valve closed and HO2S fluctuating normally, fuel integrator counts will be greater than they were during normal EGR operation. If the change is not within the calibrated window, a DTC 32 will be set.

The control module will check EGR operation when:

^ Engine speed is greater than 1600 RPM.
^ Engine vacuum is between 20 and 60 kPa (6" and 18" Hg).
^ No change in throttle position while test is being performed.

Chart Test Description
Number(s) below refer to circled number(s) on the diagnostic chart.

1. With the ignition "ON", engine stopped, the EVRV solenoid should not be energized and vacuum should not pass to the EGR valve. The EVRV solenoid will allow vacuum to pass to the energizing valve.

2. Checks for plugged EGR passages. If passages are plugged, the engine may have severe detonation on acceleration.

3. The vehicle must be driven during this test in order to produce sufficient engine load to operate the EGR. Lightly accelerating (approximately 1/4 throttle) will produce a large and stable enough reading to determine if the control module is commanding the system "ON".

Diagnostic Aids
Before replacing control module, use ohmmeter and check resistance of each control module controlled relay and solenoid coil.

Refer to "Control Module Wiring Diagram" for coil terminal identification of solenoid(s) and relay(s) to be checked. Replace any relay or solenoid if the coil resistance measures less than 20 ohms.