Chart C7 - EGR Check: Notes

The integrated electronic EGR valve functions similarly to a port valve with a remote vacuum regulator. The built-in solenoid is normally open, which causes the vacuum signal to be vented off to the atmosphere when EGR is not being commanded by the ECM. The ECM controls EGR flow with a pulse width modulated signal (turns on and off many times a second). This controls the amount of vacuum vented to atmosphere and controls amount of vacuum applied to the diaphragm. The electronic EGR valve also contains a voltage regulator, which regulates current to the solenoid to provide different amounts of EGR flow. The EGR valve also contains a pintle position sensor, which works similarly to a TPS sensor. As EGR flow is increased, the sensor output also increases.

1. Whenever the solenoid is de-energized, the solenoid valve should be closed. This should not allow the vacuum to move the EGR diaphragm. If the filter is plugged, however, the vacuum applied with the hand held vacuum pump will cause the diaphragm to move because the vacuum will not be vented to the atmosphere.
2. This test will determine if the EGR filter is plugged, or if the EGR valve itself is faulty. Use care when removing the filter to avoid damaging the EGR assembly.
3. If the valve moves in this test, it is due to circuit No. 435 being shorted to ground.
4. Grounding the diagnostic "test" terminal should energize the solenoid which closes off the vent and allows vacuum to move the diaphragm.
5. The EGR assembly is designed to have some leakage, therefore, 7 in. Hg of vacuum is all that should be held. However, if too much of a leak exists (less than 4 in. Hg of vacuum holding), the assembly is leaking excessively and must be replaced.