Vacuum Modulator Valve

1. Block drive wheels, apply parking brake and place transmission in park.
2. Start engine and run at slow idle.
3. Connect vacuum gauge to hose leading to VMV port ``M.'' If reading is less than 14 inches Hg, check vacuum pump, VRV, solenoid and connecting hoses.
4. Reconnect hose to VMV port ``M'' and connect gauge to VMV port ``D.''
5. Gauge should read 13 inches Hg. If not, VMV is defective.