IA10 - Shutter Valve Function
^ Disconnect the shutter valve actuator linkage from the shutter valve.
^ Check that the shutter valve moves smoothly from a fully closed position to a fully open position.
^ Is the shutter valve assembly free of binding or damage?
YES -- Go to IA11. IA11 - Shutter Valve Vacuum Reservoir Leakage
NO -- Replace the shutter valve assembly.