Fridgidaire dishwasher stops anywhere during cycle

My 5 year old dishwasher stops in the middle of the cycle and the green "wash" light blinks, heating light solid. It sometimes has water in the bottom and sometime it doesn’t. I turned the circiut breaker off and left it off for a while, and afterwards it went through two or three cycles ok, then started the stopping and blinking thing again. The last few times I tried the circuit breaker trick, it started washing, but stopped before the cycle was complete. I know it could be the control module, but could it be something else (heater or thermostat)? I’d hate to spend money on the wrong part. How can I test this?