Zone 1 of my 4-zone Sprinkler system will not come on when the timer trips, but if I start it manually ...?

Ours did this and the repair man said it was a short....and all he did was go to the box outside and wiggle some wires around and recap a connection....Maybe your problem too??

it sounds to me as if the solenoid of the valve was removed without shutting the water off first. common mistake with a richdale valve ,shut the water off and remove the solenoid ,look inside the slot where the solenoid was removed from .there should be a little white tit in the hole in the center of the valve body solenoid slot. if it is missing the odds of finding it are slim ,yet if you get lucky and find it reinsert it ,otherwise you will have to buy a new valve of the same type ,and remove the screws from each ,and swap the tops of the valves which is easy er than cutting it out and re plumbing it. if the valve is tripping on zone one and you have not replaced the solenoid ,SHUT THE WATER OFF and replace it with one of the same . always take the old part with you to the supply house so that you buy the same kind.

verify the timer field make confident it remains scheduled to instruct that zone on means outages on occasion interrupt a timers set scheduling verify the wires on the valve if that doesnt do it verify the valve commonly in a sprinkler device its the little stuff that forestalls working