One beep every 5 seconds on the Mighty Mule FM502 does not have a defined diagnostic purpose. However if you are possibly estimating the seconds wrong there are two diagnostics that do match up with that gate opener. 1 beep every 2 seconds: Master Arm limit switch. Here is how you will test for this issue. Remove the master arm from the master arm wire terminals. Take the slave arm motor wires and insert them into the master arm terminals. Then take the master arm terminals and insert them into the slave terminals. Power down the board and power it back up. Theoretically now you should be getting 2 beeps every 2 seconds, which indicates the slave arm has a limit switch issue. This would be because you made the master the slave. 1 beep every 10 seconds: Low battery Even new batteries can have low power before they are charged. To correctly evaluate your battery voltage put a multi-meter on the battery while the battery is under load. The battery should be above 13VDC and not drop more than 0.1 volts under load.