System Test

1. On 1984 Accord, bypass control valve by connecting hose No. 31 to hose routed to air control valve B.
2. On all models, disconnect and plug vacuum hose from power valve.
3. Start engine and allow to reach normal operating temperature, then remove cover from emission control box No. 2 on Civic models, if necessary.
4. Ensure frequency solenoid valves A and B are operating while running engine at approximately 2500 RPM. Frequency solenoid valves should click on and off continuously.

NOTE: Check frequency solenoid valve operation within 3 minutes after starting engine.

5. If both solenoid valves operate properly, proceed to step 13. If either solenoid valve does not operate properly, replace valve as required and repeat test. If both solenoid valves do not operate properly, check for voltage between the frequency solenoid valve connector terminals while running engine at approximately 2500 RPM.
6. If voltmeter indicates 12 volts and 0 volts alternately, replace solenoid valves and repeat test. If voltmeter indicates 12 volts and engine operating condition is normal, check vacuum lines for leaks or blockage and each valve for proper operation. If voltmeter indicates 12 volts and operating conditions are abnormal or engine stops, proceed to steps 7 through 12.
7. Inspect intake air temperature sensor and oxygen for proper operation. Repair or replace as required.
8. Inspect vacuum switch A, B or C for proper operation. Replace as required.
9. Check for voltage to control unit connector black/yellow wire (all models) and blue wire (Civic and Prelude) with ignition switch ON. Voltage should be present.
10. If voltage is not present, check wiring and fuse.
11. Check for continuity between control unit and suitable ground. Continuity should be present.
12. On Prelude, test 15 MPH speed sensor as outlined under "Speed Sensor, Test" procedure.
13. Connect vacuum hose to power valve, then check that frequency solenoid valves A and B are not operating while engine is idling.

NOTE: Air conditioner should be in the Off position, if equipped, while performing above test.

14. If solenoid valves are not operating, system is satisfactory. If solenoid valves operate, perform steps 7 through 12, then repeat test.