EGR Valve: Testing and Inspection

Fig.151 - Vacuum & Voltage Chart:

1. Start engine and allow it to idle.
2. Disconnect the vacuum hose from the EGR valve and connect a hand vacuum pump to EGR valve, Fig. 151.
3. Apply 150mm Hg (6 in. Hg) vacuum to EGR valve. Vacuum should remain steady and engine should die. If this occurs the EGR valve is working properly. Remove hand vacuum pump and reconnect the hose, test is complete.
4. If vacuum does not remain steady and the engine does not die, then replace EGR valve and retest.
5. Should vacuum remain steady but the engine not die, then remove EGR valve and check for blockage, also check manifold for blockage. Clean and replace as necessary and then repeat test.

NOTE: This completes EGR valve diagnosis except for 1981 Calif. models. For 1981 Accord and Prelude proceed with steps 6-13 and for 1981 Civic proceed with steps 14-28.

6. Check for voltage at EGR control solenoid valve for manual transmission or for automatic transmission.
7. If there is voltage test is complete. Proceed to step 11 for vehicles with automatic transmission.
8. If there is no voltage, disconnect connector from thermosensor and check for continuity with coolant temperature above 149° F.
9. If there is no continuity, replace thermosensor and retest.
10. If there is continuity, check electrical connections.
11. Raise and support front of vehicle, block rear wheels, and apply hand brake.
12. Push voltmeter positive probe into yellow/black wire and connect negative probe to suitable ground.
13. If there is no voltage, check wiring, replace speed sensor as necessary, and retest.
14. If barometer switch has no continuity, jump wires at barometer switch connector.

Fig.153 - Proper Voltmeter Connection:

15. Push voltmeter probes into indicated terminals at control box No. 3 connector, Fig. 153.
16. Check for voltage at idle.
17. If there is no voltage, disconnect connector from thermosensor and check for continuity with coolant temperature above 158° F.
18. If there is no continuity, replace thermosensor and retest.
19. If there is continuity, check electrical connector and retest.
20. If there is still continuity, raise and support front of vehicle, block rear wheels, and apply hand brake.
21. Raise speed above 15 mph and check for voltage at EGR control solenoid valve connector.
22. If there is no voltage, check vacuum switch for continuity.
23. If there is continuity, replace vacuum switch.
24. If there is no continuity, replace speed sensor and retest.
25. If there is voltage, disconnect hose leading to vacuum switch at vacuum manifold with speed above 15 mph.
26. If there is no voltage at EGR control solenoid valve replace vacuum switch.
27. Connect vacuum gauge to hose No. 2 vacuum outlet.
28. If there is no vacuum, clean orifice in vacuum manifold and retest.