How to Test & Troubleshoot Your Garage Door Automatic Safety Reverse Sensors

Federal law requires all residential automatic garage door openers manufactured after January 1, 1993 to be equipped with safety reverse sensors. This important safety feature is designed to protect your family and pets from accidental injury or death due to entrapment. It works by automatically reversing the direction of the closing garage door in the event that it makes contact with a person or object in its travel path.

It's important to note that any residential automatic garage door opener manufactured after this date will not even travel in the down direction without a properly connected and functioning automatic safety reverse mechanism. If the opener will not automatically activate the door due to an issue with the safety reverse sensor, simply press and hold the door control button to close the door.


Testing the automatic safety reverse sensors is an easy task to perform once a month. It costs nothing, only takes a moment to complete and helps to ensure the overall safety and health of your automatic garage door opener system. Follow these simple steps to test your garage door's automatic safety reverse sensors:

  • Place an object (such as a brick) on the ground directly in the path of the door.
  • Activate the garage door opener to close the door on the object.
  • The door should automatically reverse when it makes contact with or "senses" the object in its path.
  • If the door does not automatically reverse when it makes contact with the object in its path, some additional troubleshooting may be necessary.


If you experience difficulty with one or any of the steps in the testing process, misaligned sensors or faulty wiring could be the cause of the problem. To determine if the sensors are misaligned:

  • Observe the LED indicator lights on the sending and receiving sensors. If they are flashing and not solid, the safety beams are either misaligned or there is an obstruction in the beams path.

Wiring issues such as a disconnected wire, improper wire connection, poor wire connection or a shorted wire could also cause the safety reverse mechanism to malfunction. If you suspect a wiring issue:

  • Inspect the wiring to determine if the safety reverse sensors are wired incorrectly or disconnected entirely.
  • Wires are generally color-coded to matching terminals. Locate the white and gray terminals on the back of the operator. White wires should be connected to the white terminal and black/white wires should be connected to the gray terminals on Chamberlain, LiftMaster, Sears, and Raynor brand openers. On Genie openers, the wires can be connected to any terminal as they do not have polarity.

If the wires appear to be connected properly, here is a simple way to test for a shorted wire:

  • Disconnect the sensors from the brackets.
  • Detach the wires from the wire nuts or snip them approximately 12" from the sensors.
  • Strip the wires on both ends and twist the matching colored wires together on each sensor to the motor of the garage door opener.
  • Unfasten the wires from the operator terminals and reconnect them according to color to the matching terminals.
  • Direct the sensors at each other - if the LEDs on both sensors light up, there is a problem with the wiring. Replace the wires.
  • If the LEDs DO NOT light up, replace the sensors.
  • If the LEDs still do not light up after replacing the wires or sensors, replace the logic board.

If your openers safety beams are not lit, here are a few things that may be the cause:

  • Wires are not connected at the beams and/or the back of the unit.
  • Your safety beams got wet and need to be replaced
  • Your opener recently suffered a power surge- either from an electrical storm or power outage. If this is the case, the beams will likely be fine but you will need to replace your garage door opener's circuit board.

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