What could be causing my garage door to randomly open and close?

Question

A few mornings ago, my wife and I noticed that our garage door started opening and closing with no discernible pattern. It would stay closed for some period of time, open suddenly, and sometimes reverse direction. We located all the garage door openers, relocated the remotes far from radio range, are fairly certain that somebody isn't playing a cruel joke on us.

Our working theory on the root cause is an electrical outage that occurred two nights earlier had fried the circuitry. The safety sensors that stop the door appear to be untouched, and the system generally seems unchanged from before the electrical outage. Pressing the remotes or the hardwired controllers appear to normally operate the garage door.

Before we go ahead and replace the garage door opener, what other steps would you recommend we take to diagnose further?

UPDATE [3/30]: Thanks for everyone's help! I didn't have a chance to try out everyone's suggestions until a few days ago. In the meantime, I unplugged the garage opener and manually operated the door. I didn't expect the door to reattach to the garage opener, and unfortunately, the only entrance to my detached garage is through the garage door. Luckily, one of the windows to the garage was unlocked, so my wife and I hilariously broke into our own garage! In any case, I detached the low voltage and control lines, plugged the opener back in, and left the garage door closed for an hour.

As far as I can tell, the garage door remained closed. I plugged in the low voltage and control lines, and the garage opener continues to operate normally. Perhaps, keeping the power off for an extended time helped? I'm officially stumped.

UPDATE [4/21]: I disconnected the low voltage/control wires from the connector at the opener, and the garage door opener hasn't randomly opened. I can still open and close the door with the remote, so isolating which of the two hardwired control lines is randomly triggering the opener.

Answer 1

First rule of electricial/electronics is cycle power to see if that solves the problem. Unplug it - give it a few minutes and then plug it back in. If the random openings stop, the unit just needed a hard reset.

Next Up - Disconnect the low voltage/control wires from the connector at the opener. If the door still opens randomly then the problem is in the opener itself.

If the random openings stop, hook the low voltage cables back up to the opener.

If the random openings start again, the problem is in the control side of things.

Remove and replace as needed.

Answer 2

1) Regarding the door re-attaching - there should be a way to disconnect the opener from the door that prevents the automatic reattachment. Look closely at the mechanism. You might need to pull down on the release cable (like normal), then pull it back a bit to get the device to lock.

2) The random opening could be caused by RF interference. A high power RF signal from a CB or amateur radio operator might be setting it off. Disconnect the control lines at the motor and operate the door ONLY via the remote for a few days. If the problem goes away, re-attach the wires and see if the problem returns. If the control lines are the culprit, running them through appropriate ferrite chokes might cure it. For ex. Mouser p/n 623-0431164281