Look on the inside of the front panel door or the back of the plastic casing. "ISA 304" indicates:
Do not confuse this with: The Rain Bird ISA-406 (6 zones) or the newer SST series.
Given its age, you might wonder if replacing the ISA 304 is better than repairing it. Here is the manual’s unspoken advice:
Repair if: The clock motor hums but turns, the metal casing is intact, and you only need 4 stations. Replacement gears and transformers are available on eBay.
Upgrade if: You have lost the station pin wheel, the plastic is brittle, or you want Wi-Fi control (look at the Rain Bird ESP-TM2 or ST8-WiFi).
Miswiring is the #1 cause of "timer failure" (which is actually user error). According to the official Rain Bird sprinkler timer isa 304 manual, follow these rules:
Before programming, locate these physical components on your unit. The manual refers to them constantly:
