This will explain how to troubleshoot a garage door opener that won’t close the door and blinks 10 times. Mostly, this indicates the garage door sensors are out of alignment,  or there is something in the way of the sensors. Garage door openers made after 1993 are equipped with sensors positioned on both sides of the vertical rails. They work by sending and receiving an invisible infra red beam. If there is something in the way of the beam, or if the sensors are out of alignment. The opener will not close the door, thinking there is something in the way. There is no way to bypass this functions.

First thing you need to do is make sure there is nothing in the way of the sensors and they are pointing at each other. This in 90% of the times fixes the problem in a minuet.

My sensors are aligned and there is nothing in the way. Why doesn’t my garage door close?!

If that’s the case, you should check the wiring leading from the sensors to the motor. look for crossed wires or defective wires. Sometimes the wires get disconnected from the opener or the sensors anchoring base.



Further troubleshooting for LiftMaster\ Chamberlain\ Craftsman garage door openers


Garage door safety sensors are made of a “sender” and a “receiver”.

Lift master\ Chamberlain\ Craftsman will typically have the “sender” sensor equipped with a yellow service light indicating it is sending a beam. The “receiver” sensor will have a green service light that only lights up when it “catches” the signal from the sending sensor unit. if you garage door sending sensor is showing a yellow light and the other does not show a green light -it is likely they are misaligned.

You may want to check the back of the motor unit. The back of the motor has a circuit board with a service light as well. The blink rate on the garage door opener service light points to various error codes.


Older units will show this:

1 blink – sensor wire are disconnected

2 blinks – sensor wire are shorted

3 blinks – sensor eyes misaligned


Newer units with arrow light up buttons

Up 1 blink, down 1 blink – sensor wire are disconnected

Up 1 blink, down 2 blink – sensor wire are shorted

Up 1 blink, down 4 blink –sensor eyes misaligned/obstructed

Up 4 blink, down 6 blink – sensor eyes misaligned/obstructed temporarily


If both sensors light up and the door still does not close, it could be your sensors are just faulty. Like any electric component, garage door sensors sometimes need to be replaced. before replacing your garage door sensors, it is a good idea to verify the sensors are bad. cut the sensor wires 4″ from the sensors and try hooking them up directly at the motor. Align them properly and see if the door now closes. This will help you eliminating a wiring problem. If the door still does not close you most likely have a faulty sensor or a faulty circuit board.