The Mighty Mule MM360 opener bought from Tractor Supply on 12/15/2018 failed about October 15, 2021.
10/21/2021 – Bought the current replacement model MM371W. It was operational on 10/22/2021.
10/4/2026 – Replaced antenna and remotes. See below for deails.
FM143 – Automatic Gate Lock
Installation Manual & Troubleshooter here.
https://www.youtube.com/watch?v=A-eGO8UmTJY&ab_channel=TipsNNTricks
https://www.mightymule.com/wp-content/uploads/FM143-Auto-Gate-Lock-0525-10024428-Rev-B.pdf
10/4/2026 – Gate opening and closing randomly.
Over the past weeks we found three or four times the gate open in the morning.
Asked ChatGPT for ideas. Prompt: Could rain cause the gate to open and then close hours later?
Rain entering the damaged antenna area could contribute to an intermittent electrical problem, but it is unlikely to be the direct cause of the delayed closing. Here is how I [Chat]would separate those possibilities.
- Rain and moisture: If water reaches damaged insulation, it can enter the cable or connector, particularly if the shielding or inner insulation is also compromised. Moisture can cause corrosion or intermittent electrical behavior. If only the outer jacket is chewed and the underlying cable remains intact, rain is less likely to cause an electrical fault.
- Unexpected opening: The antenna receives radio commands at 318 MHz. The damaged cable could affect reception, but water in the damaged area is not, by itself, evidence that a false opening command is being generated. The manufacturer’s MM371W/MM372W manual describes the antenna and receiver arrangement.
- Delayed closing: These openers can have an automatic-close timer. The manual also explains that certain safety inputs can prevent closing or restart that timer. Thus, if a gate opens and remains open for hours, a timer setting or a continuing safety-input condition may explain the delay better than the damaged antenna alone. [this feature was not activate so not the issue]
What I would do next
- Replace the antenna first. Given the squirrel damage at the base, replacing the complete antenna is a straightforward way to eliminate that damaged component as a variable. The manufacturer lists the RP1008 as compatible with the MM371/MM372 family, although availability may vary. RP1008 antenna. Mighty Mule
- Protect the connection from further moisture and animals. Install the replacement as directed, with the antenna upright and its connector properly tightened. Do not wrap the antenna itself in metal foil or enclose it in metal.
- Observe the gate after rain. Record whether it opens unexpectedly during or after rainfall, and whether it subsequently closes on its own. Because the fault is intermittent, monitor it for several weeks.
- If the gate still opens unexpectedly, investigate the receiver and control board. Do not assume the antenna was the cause merely because it was damaged.
We replaced the antenna and cable as well as the remotes as one of them was 8 years old and the other two are 5 years old. The new parts listed below were bought through Amazon.
- RB741 for Mighty Mule Gate Opener Remote, 318MHZ
- Smart Gate Door Opener Extended Long Range Receiver Replacement 433MHz Antenna for GTO Mighty Mule MM571W MM572W MM371W MM372W MMS100 LiftMaster Ghost Controls Automatic Garage Gate Opener?Eifagur
