I recently bought a home built in 1992 with irrigation installed at that time. I have 4 missing control values, probably in one box, that has been covered up over the years with mulch and bark. I am aware that Irritrol has a controller that will cycle the control value(s) on and off, making the solenoids click. Supposedly, by listening for the click, one should be able to locate the missing values.
@PocketLab Yes, turning on a zone, will cause the solenoid valve to click. You can usually hear it if you’re close to the valve box.