M,

Replace the solenoid on the auto valve that stays on. They are not expensive and are easily replaced. Is it just one zone? Do you know how to turn a zone on and off manually by using only the the solenoid? You can do this with the system completely shut off. let me know. Aloha

Most irrigation timers run on 24 Volts AC and use what's called a TRIAC to switch the AC power to the valve solenoid.
Triacs are semiconductors and are sensitive to above-normal volages so any voltage "surge" like lightning or incoming power can damage them. And they usually fail "ON".

This controller may be able to be repaired and TRIACS for that application are cheap. But it's probably more trouble than it's worth.

For more information send an e-mail to: pumpsys@embarqmail.com