Liftmaster GDO opens on its own

seashells18March 24, 2011

I have a Liftmaster Elite model 3850 opener. It was installed about 7 months ago by a professional door company. Suddenly, the door has started opening (not closing) on its own. The LED light on the main unit is steady green. The company that installed it came out and wasn't especially helpful. The tech seemed skeptical that there was a problem at all. He replaced the wall control unit, but that has not solved the problem. I told the service tech that I saw a brief message on the LED readout that said something about miswiring. I only saw this message once and didn't see the entire message as it was scrolling across the screen. He didn't seem to be interested in that bit of information. I took the batteries out of the spare remote to be sure that wasn't causing a problem. Any ideas?

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The steady green light on the motor unit is an indication of interference. Random flashing is normal. I would look for an old remote in a drawer or shelf that has a bad switch or something on top pressing down on the button. To eliminate the possibility of a staple shorting out the wiring to the wall control you can temporarily remove the wire from terminal #1 on the rear of the motor unit. If you cannot find the interference I would suspect the logic board.

    Bookmark   March 25, 2011 at 9:50AM
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Thanks for the info. The green light was actually the battery back up indicator. Indeed, the logic board was bad. All is well now!

    Bookmark   April 2, 2011 at 10:45PM
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