Civic 1500
- Remove cover to control box number 2. Disconnect the hose between the constant vacuum valve and frequency solenoid valve B. Connect a vacuum gauge to hose.
- Start engine and run at idle speed. Check that vacuum gauge stabilizes at 6-11 in. Hg (man. trans.) or 2-7 in. Hg (auto. trans.). If vacuum is within range, constant vacuum valve is okay. If not, replace constant vacuum valve and retest.