Dishwasher problem.

Dishwasher functions Ok except for the display changing time durations for different wash cycles. For example on normal wash the display will change from 89 minutes to 88, or 87, or 86 minutes. I suspect the control board (WD21x10215) but am unable to locate a tech. data sheet to let unit self diagnose. Any suggestions, as I don’t want to shotgun parts at the problem??