A control system for an inflatable support mechanism having a fluid inlet includes at least one inflate valve including an inlet, and a purge valve including an inlet portion and an outlet portion. The inlet portion is fluidically connected to the inlet. No more than one absolute pressure sensor is fluidically connected between the fluid inlet and the inlet of the at least one inflate valve and the inlet portion of the purge valve the no more than one absolute pressure sensor selectively sensing pressure within the inflatable support mechanism and atmospheric pressure.