EGR System Check (EVRV Solenoid)

EGR System Check:

Wiring Diagram For EGR System Check:

EGR SYSTEM CHECK (OVER 8500 GVW)

CIRCUIT DESCRIPTION:

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

The PCM monitors the effectiveness by de-energizing the EGR control solenoid, thereby shutting off vacuum to the EGR valve diaphragm. With the EGR valve closed and the 02 sensor 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 code 32 will be set.

The ECM will check EGR operation when:

^ Engine speed is greater than 1600 rpm.
^ Engine vacuum is between 20 and 60 kPa.
^ No change in throttle position while test is being run.



TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. With the ignition "ON", engine stopped, the solenoid should not be energized and vacuum should not pass to the EGR 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 will produce a large and stable enough reading to determine if the ECM is commanding the system "ON."


DIAGNOSTIC AIDS:

^ Before replacing PCM use ohmmeter and check resistance of each ECM controlled relay and solenoid coil. Refer to PCM QDR Check.

See PCM 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.