System Diagnosis

Cold Engine

1. Engine coolant temperature must be below set temperature of thermosensor (thermosensor "A" on 1981-82 models) and thermosensor must have continuity.

2. Disconnect vacuum hose from EGR valve and connect vacuum gauge to hose.

3. Start engine and raise engine speed to 4500.5000 RPM.

4. If vacuum is not available, proceed to hot engine inspection, except on 1981 models, for which you should proceed to step 8.

5. If there is vacuum, check for voltage at EGR control solenoid valve (EGR control solenoid valve "A" on 1981-82 models).

6. If there is voltage, replace EGR control solenoid valve and retest.

7. If there is no voltage, check thermosensor operation (thermosensor "A" on 1981-82 models), wiring, and fuses, repair or replace as necessary and retest. This completes cold engine inspection except for 1981 models.

8. On 1981 Civic, connect blue/yellow and yellow/white wires together using a jumper wire at barometer switch connector.

9. Check for voltage at EGR control solenoid "B" ("D" on Accord and Prelude with automatic transmission) with ignition switch on.

10. If there is no voltage, proceed to hot engine inspection.

11. If there is voltage, disconnect connector from thermosensor "B" and check for continuity with coolant temperature below 158° F for Civic or 149° F for Accord and Prelude.

12. If there is continuity, replace thermosensor "B" and retest.

13. If there is no continuity, check wiring and repair or replace as necessary.

14. Remove jumper wire on 1981 Civic.

15. On 1981 Civic, check for continuity across barometer switch. At altitudes below 2300 feet, switch should have continuity. Reconnect barometer switch.

Hot Engine

1. Disconnect vacuum hose from EGR valve and connect vacuum gauge to hose.

2. On 1981 Accord and Prelude, remove control box cover attaching screws (3) and remove cover.

3. Push voltmeter positive prohe into yellow (1980), blue/white (1981), blue/yellow (1982 Accord), or blue (1982 Civic and Prelude) wire terminal at control box connector (control box No. 2 on 1982 Civic and Prelude) and connect negative probe to suitable ground.

4. Raise and support front of vehicle, block rear wheels, and apply hand brake.

5. Start engine and allow it to reach normal operating temperature.

6. On 1982 Accord, remove control box by removing five mounting bolts from fire wall, then remove control box cover by removing 4 attaching screws.

7. Check that vacuum and voltage appear as indicated in appropriate chart, Figs. 150. For 1980 Accord and Prelude, remove plastic cap from EGR bleed before testing.

8. If Readings are incorrect, refer to appropriate troubleshooting condition.