On the Head Puck - A red blinking LED indicates an error. This typically means that more than one zone is turned on at the controller for a few seconds. A common reason for this is that the water hammer feature is turned on at the controller and needs to be turned off. In some controllers such as the Rainbird controller this is called the 'Delay Between Valves' feature which allows you to set a delay between one valve turning off and the next turning on. Specifying a delay of just a few seconds will be sufficient.A green blinking LED is the normal mode of operation. The LED will blink a pattern that indicates which zone is on. For example, 5 consecutive blinks followed by a 3 second pause indicates that zone 5 is on.On the Tail Puck - The LED will blink green fast for about 3 seconds when first turning on. This indicates that it is initializing and receiving the necessary information from the Head Puck about which zone to turn on. After this happens, the green LED will blink the same pattern as the Head Puck, a pattern indicating which zone is turned on. For example, 2 consecutive blinks followed by a 3 second pause indicates that zone 2 is on. If that pattern blinks red, it means communications are struggling. The system can usually still operate in this condition, but may be indicative of a wiring issue between the head and tail pucks. If the red LED blinks continuously it means the communications have failed entirely and all zones will be turned off until successful communication resumes.