I am trying to hook up my new rachio 3 straight to main valve with only 2 wires. I put them on c control and m main. But the solenoid makes a loud buzzing noise and does nothing. Is it wired wrong?
I presume you are talking about the master valve? What brand and model is it? It sounds like it is correct with the M (master valve terminal) and C (common wire). I wonder if the valve uses different voltage, has an issue, or something. Does it work with your old controller? If so, can you measure the voltage from the old controller?