Chris,
It sounds to me as if the valve that controls the #3 zone has failed open with a master valve keeping it from running all the time, even with the controller off. Replace #3 and you will resolve your problem.

All Wet
Texas Licensed Irrigator #1897 since 1984

thanks I will try that

I believe that "all wet" is correct in his diagnosis. Taking out a valve is a job that will take the better part of an afternoon. I'd try replacing the diaphram, solenoid, and bonnet before complete removing the valve.

if zone stays "on" then diaphram is bad or there is dirt inside, remove cirlce of screws around valve body and pull diapram, inspect, clean, put back and test

if zone WON'T turn "on" then valve solenoid is bad