zone 2 heads come on for both zone 2 and zone 3
Up until 4-6 weeks ago my system was working fine. For unknown reason(s), now zone 3 does not work. When I use the controller to manually turn on each zone, when I turn on zone 3, the heads in zone 2 come on (but not the heads in zone 3). When zone 2 is turned on manually, those heads do come on correctly, so the wiring is not simply switched. I tried moving the wire from zone 3 to zone 6 (currently empty), but that did not change anything -- zone 2 heads still came on. The controller is a Rain Bird SST-600i, if that makes any difference.
Any ideas?