On Jan 26, 10:37 am, wrote:
I've got an underground sprinkler ...looks like ...seven zones ...found a buried control box for
four zones [but] can't find a second control box. ...

If the suggestions of the previous owner or the logical plan/layout
don't pan out, the underground wire tracer is the next best bet. I'm
fortunate to have a friend who did the sprinkler stuff for a while and
had one to borrow, you may find one at a rental or might just bite the
bullet and call a service company to help locate it the first time.

I've no idea whether could find one to rent---that's also a
possibility. Haven't looked into how inexpensive a current one might
be had for, either--others likely can also provide that info.