Liftmaster Garage Door opener troubleshooting

How to test or troubleshoot the safety reversing sensors

The safety reversing sensors must be connected and aligned correctly before the garage door opener will move in the down direction. Typically issues with the safety sensor wiring occur because of a poor connection, incorrectly connected wires, or a short in the wire from a staple.

NOTE: If you are unable to get the door closed and the safety sensors are the issue, the garage door can be closed by pressing and holding the Door Control push bar until down travel is completed.

If both safety sensor LED lights are not lit

Security+ 2.0 garage door openers have an energy conservation feature. If the garage door opener is Security+ 2.0, have the customer activate the door to determine if the opener was only in sleep mode. See Security+ 2.0 energy conservation feature

Inspect the wiring

  1. Check for incorrect wiring between the sensors and the garage door opener.
  2. Verify the wire connections are correct on the garage door opener. The solid white wires connect (insert) to the white terminal (2) and the white/black wires connect to the grey terminal (3).

NOTE: The amber LED on the sending sensor will glow regardless of alignment or obstruction. If the green LED on the receiving sensor is off, dim, or flickering (and the invisible light beam path is not obstructed), alignment is required. See How do I align my safety reversing sensors?

Test the safety sensor wires

  1. Remove the sensors from the brackets.
  2. Remove the wires from the wire nuts or cut the sensor wires 12" from the sensors.
  3. Strip both ends of wires from each sensor and twist like colored wires together. Proceed with both sensors to the garage door opener motor unit.
  4. Remove existing wires from the white and grey terminals on the back of the operator.
  5. Attach or insert white wires into the white terminal and black/white striped wires into the grey terminal.
  6. Point the sensors at each other - if both sensor LED's turn on, there is an issue with your wiring. Replace the wires between the opener and the sensors. If the LED’s DO NOT turn on, replace the sensors.

Note: If after replacing the sensors, the LED's still do not light, replace the logic board.

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