Garage Door Opener Short “UP - Down” Movement

Fixaya says:

“If you have increased down force threshold and the door continues to reverse, the RPM sensor is the culprit. There is no way to override or test this sensor by using the hand unit or the wall control. When this sensor goes bad the door will start down and the logic board will not receive the electronic pulses and it will reverse. It is this sensor that causes the door to reverse when it runs into something. The motor stalls, the logic board doesn’t receive these pulses and it reverses. This little circuit board is located at the door end of the motor shaft and every door company has them in stock.”

RPM sensor.JPG

So... what do you think? Please leave me a comment.


  • David: Thank you. I will try this
  • charmmuggie: Thanks for the great advise. I have saved it for future use. However, the door was not reversing, but only stopping every few inches. I finally discovered that one of the wires from the house power source had a poorly crimped connector on the end of it. Over time, the normal movement of the lift unit allowed the wire to loosen and slightly pull out of the connector. When the lift unit was activated, it would jiggle the wire enough to make it short out. When the lift unit shut off, the wire would once again make contact inside the connector. Therefore, the start/stop problem. I replaced the connector on the wire and, "BINGO," problem solved. Thanks again!!
  • metro17: Eureka I kicked the down pressure up a notch or two and it has performed wonderfully since. Thank You for your help. I could not have figured it out without your help.
  • Brian: Yep, that fixed my problem. First I replaced gear and sprocket when door would no longer open, then it would only go 6 inches and reverse itself. This part fixed my problem.
  • will quest: i change the plastic gear and sensor still the liftmaster door open 5 to 6 inches any thing else to change? thank you for your help
  • Bob: I changed out the sensor from my working door and same problem still the same problem with the door raising 10 inches and going back down
  • AG in Tucson: Thanks so much. I notice that the sensor was vibrating because one of the tabs that holds it to the metal was broken. I got the sensor asm. installed it and works like new. The sensor asm. was only 15.00 bucks. Thanks again and have a good day.
  • George Bower: My garage door goes up about a foot and stops. I noticed that the cable on the left side is not rolling up correctly. I am scared to try to turn the spring roller in fear of being hurt. Any help?

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