Vacuum Testing the One-Way Check Valve

1. In the engine compartment, disconnect the vacuum supply (black) hose. This hose passes through an opening in the dash panel.
2. Remove the vacuum check valve. This valve is located on the (black) vacuum Supply hose at the right side of engine.
3. Connect test vacuum supply hose to the control module side of the valve. In this direction the gauge should return to calibrated setting. If valve leaks vacuum in this direction, valve replacement is necessary.
4. Connect test vacuum supply hose to the engine vacuum side of the valve. Vacuum should flow through valve.