Port EGR Valve

EGR System Check:

Circuit Description:
The ECM operates a solenoid to control the exhaust gas recirculation (EGR) valve. This solenoid is normally closed. By providing a ground path, the ECM energizes the solenoid which then allows vacuum to pass to the EGR valve. The ECM control of the EGR is based on the following inputs:

^ Engine coolant temperature - above 25°C

^ TPS - "OFF" idle

^ MAP

If Code 32 is stored, DTC 32 Code 32 will detect a faulty solenoid, vacuum supply, EGR valve or plugged passage. This chart checks for plugged EGR passages, a sticking EGR valve, or a stuck open or inoperative solenoid.

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. Grounding the diagnostic terminal will energize the solenoid and allow vacuum to pass to the valve.

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

4. 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 ECM is commanding the system "ON".

Diagnostic Aids:
Before replacing ECM, use an ohmmeter and check the resistance of each ECM controlled relay and solenoid coil. and ECM wiring diagram for coil terminal "ID" of solenoids and relays. Replace any solenoid where resistance measures less than 20 ohms.