According to the Rainbird Specifications “ The sensor shall be wired to normally closed (N.C.) controllers – in series with the valve com- mon, or alternately, wires shall be inserted into the appropriate controller sensor terminal ports.“
Since the Rachio instructions say “ * Sensor ( S1 , S2 ) terminals - use S1 or S2 for a single sensor, NOT both
- Sensor common ( 24 VAC - ) terminal. This corresponds to the SC terminal on the Generation 2
- Sensor power ( 24 VAC + ) terminal - for wireless (powered) rain sensors . This corresponds to the SP terminal on the Generation 2.”
I believe you should move the white wire from 24v- to SP2 as it appears that the white wire is the rain sensor wire and should be connected to a sensor terminal not the common terminal.