Question
I have a rain bird ESP 6TM that is flashing "Err" and won't come on.  It alternates between the normal display and the Err message.

Answer
Hey Gil, when it says "err" it means one or more of the valves is shorting out the controller, and so it trips an internal circuit breaker so it doesn't damage the controller. Normally it should say err and a number to indicate what number valve is shorting out. Put the clock in the "auto" position and hit the "off" button and it should take the err message off. Now to find out what valve is shorting out the controller, turn one valve on at a time manually by the controller, and when the valve # is turned on that is shorting out, it will immediately show "err". Once you determine which valve(s) is shorting out the controller, you need to either replace the solenoid on that valve(s), or if it is not the solenoid, check the wiring and determine where it is shorting out. Good luck and have a great day.