There are two hoses going into the cruise servo. The smaller hose is a vacuum supply, and the larger hose is the dump hose. First, check the vacuum-supply hose using a vacuum gauge. It should read between 15 and 20 inches of vacuum at idle. If not, check the hose for leaks. This hose originates at the right side of the intake manifold under the fuel-rail cover. There you will find a solid black or a black-and-white vacuum check valve with three ports just below the fuel-pressure test port.