Constant Vacuum Valve: Prelude

Disconnect hose number 30 from the frequency solenoid valve B and connect a vacuum gauge to hose. See Fig 1 .

Fig 1: Checking Constant Vacuum Valve Accord model shown; Prelude model similar.
Start engine and run at idle speed. Check that vacuum gauge stabilizes at 4-8 in. Hg. If vacuum is within range, constant vacuum valve is okay. If not, replace constant vacuum valve and retest.