Here are the connections I made from the Rainbird WR2 wireless rain sensor to the Rachio Generation 2 controller. Once you’ve made the connections, you can insert a flathead screwdriver into the top of WR2 sensor to depress the switch, actuate the sensor, and verify the sensor activation appears in the Rachio app’s activity log. Jeremy from Rachio support verified this wiring is correct.
WR2 wire --> Rachio connector
Green sensor --> S1
White common --> SC
Black 24VAC --> SC
Red 24VAC --> SP
