A control system and method for detecting variable load types and controlling the operation of a PTO clutch to effect engagement of the clutch with variable loads, and especially to more optimally effect the engagement of a clutch with a very light load or an associated over-running clutch is disclosed. The control system includes a controller that receives input and output clutch shaft speed signals and generates control signals to control the pressure applied by the clutch. If no appreciable engine droop is detected at the time of initial movement of the output clutch shaft, the load is considered to be of a very light load type, and a set of control signals based upon such load type designation, which control signals define a control curve that is flatter and more gentle than would otherwise be considered desirable, is thereafter applied to the clutch to effect engagement of the load.