I've been been mulling this around in my mind for the last few days and can only offer this;
Check and make sure all the clocks fire at different times. (Unless the pump can handle the volume and pressure of water needed to run all 3 at once.) There's a chance all 3 clox are of the same Mfgr. and the elec service may have gone out, resetting them to safe mode.... all starting at the same time of day with the same back up program.
CAN or does the system have auto start ability? Might all 3 clox have a pump start/relay?
If you can override the pump and get it going, go thru' all the working zones of all 3 controllers and make sure they are up to snuff... THEN try to run 2, then 3 clox at once... you might find you don't really have a big problem. The pump might only be able to run one system at a time. If that's it, start the clocks at 8 hour intervals opposing one another.
Good Luck!,
The Irrigation Specialist Mfg' Az.
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