Rain Dial RD-600: Zone 2 Stops Early, Zones 3-4 Don't Run—Controller or Transformer?

4-zone Rain Dial RD-600. Zone 1 runs fully. Zone 2 starts but stops minutes early (display shows running). Zones 3-4 don't start (display shows running). Manual operation at valve box works fine for all zones.

Troubleshooting Steps

1. Controller reset: Unplug, remove battery, wait an hour, reinstall, reprogram, test.
2. If no change → new controller needed.
3. Isolate transformer: Set zone 1 to 0 min. Start system on zone 2. If zone 2 runs fully but fails on zone 3 → possibly just a bad transformer. "If the transformer is extremely hot (can't keep hand on it) it's a good indicator."

The fact that manual valve operation works perfectly confirms valves and wiring are good. The controller's inability to sequence zones points to its output circuitry or transformer.