I had the same problem in two bays today. There was a high and low pressure problem. I was thinking that it had to be related but the equipment was not in the some equipment cabinet. Both of the bay timers were working correctly and stealing money.
The first think I did was check both the high pressure motor starters. By pressing the over ride button. They both worked. Then I checked the voltage to the transformer it was receiving the correct voltage. But was not getting voltage from the bays. So I check the first bay and the 
timer plug was slightly out. Plugged it in and it worked fine. The next bay I noticed the 
fuse was broken. This fixed the low pressure and I looked at the motor starter again and hit a little blue button to reset it then everything worked okay.