An electro-hydraulic control system is provided with a diagnostic system that uses extensive multiplexing of pressure switches to reduce the number of required components. The control system includes a controller with a pressure switch diagnostic system having first, second, third and fourth pressure switches each having a high and a low logic state, first and second logic valves each movable between a respective first position and second position, and first, second, third and fourth trim valves each movable between a respective first position and second position. The pressure switches are multiplexed to report one of the high and low logic state to the controller in accordance with a relatively high and low fluid pressure, respectively, at different ones of the trim valves and logic valves, thereby enabling a determination of a change in or failure to change position of the respective the trim valves or logic valves.