The first is an obstruction in the path of the door and therefore in the path of the sensor.
Garage door safety turn on light sensor not working.
A common cause of a malfunctioning garage door sensor is lack of power supply.
If your craftsman garage door opener fails to close the door properly you may need to disable the sensor light temporarily until you can replace the sensors.
According to liftmaster issues with the safety sensor wiring typically occur because of a poor connection incorrectly connected wires or a short in the wire from a staple.
Raise the garage door using the control button on the garage wall or the remote control unit from a vehicle.
Look for small led lights on the sensors.
Two types of accidental obstructions can cause the safety sensor to prevent a garage door from closing.
The sensors have to be aligned with each other and also have to be connected correctly to the garage door system in order to work.
If you find the lights turned off in one or both the sensors it indicates that there is a problem in power supply.
Inspect each sensor to make sure the green or red power indicator lights are.
When the infra red sensors are malfunctioning usually one of the sensor lights will be blinking.
All garage door openers use a sensor light to prevent the door from closing when an object is in its path.
For people who do not know the transmitter has the yellow light and the receiving sensor has the green light.
If they re turned on in both the sensors then there is no issue with the power supply.
If you do not see a solid illumination or your garage door is not working the problem is most likely due to the sensors being out of line.
Sometimes the sensor becomes faulty and needs to be replaced.