Recommended Procedure (Without Scan Tool)
Install a "T" (manufactured locally out of common fittings) into the Manifold Absolute Pressure (MAP) sensor line that comes from the intake manifold. See Fig 1. Make sure the MAP sensor is hooked up for this test. Connect a 0-30 psi gauge to "T" that is temporarily installed in the cab. Route the hose so that it is not crimped and does not come in contact with any hot surface. Operate vehicle as described in RECOMMENDED PROCEDURE.