I went on my RKE head unit and found I could use the pump function and set a output as WM A through WM C. A and B cycle back and forth and C and D cycle back and forth. In menu under general there is Wave Maker A/B and Wave Maker C/D. Selecting one of them will let you set the amout of on timer for each. It also has a random setting. If I remember correctly that will randomize the amount of time each is on with the max at the setting but I am not sure on that. I think the RKL has only A/B set.