Pulse actuated binary fluid responsive logic elements are connected in a control system for a fluid flow network operating a fluid responsive mechanism. The logic elements are interconnected to respond to a trigger pulse and automatically sequence through a cycle of operation sensing and responding to fluid pressure conditions at control points in the flow network. A portion of the control points are monitored with diagnostic binary pressure indicators to indicate the status of the network during the control sequence by display of binary words. For correcting malfunctions a comparison chart indicates the nature of invalid words and the corresponding procedure for correcting the malfunctions sensing that word structure, thereby expediting servicing by semi-skilled personnel without detailed knowledge of the system operation.