How to Troubleshoot a Garage Door that Won't Close
There are two main reasons for a garage door failing to close. The first and most common is a problem with the safety sensors.
The second is your garage door opener’s pressure sensitivity (also commonly called the “force setting”), which is designed to reverse the door if it encounters an obstruction. Any solid object taller than about 3/4” that finds itself under the door *should* cause it to reverse on contact. But it doesn’t have to be something on the ground. Anything that causes your door to run poorly, or bind, can trigger a pressure reversal. So can worn out opener parts like stripped gears and worn trolleys.
This is where the inexperienced technician or homeowner can go down the wrong track, trying to fix something that isn’t broken and complicating the problem.
Note: Never pull the manual release when your garage door is open unless you are 100% sure you do not have a broken spring! It could crash to the floor which is extremely dangerous and can do major damage to your door or anything it lands on.
A Logical Order
In order to avoid unneeded frustration, it is important to work in a logical order:
- Determine if it’s the sensors or something else
- Check that the sensors are aimed well
- Inspect wiring and splices
- Rule out faulty sensors or circuit board
Safety Sensors vs Mechanical Issue
Assuming your garage door does NOT have an obvious problem with it (e.g. it has gone crooked, has a broken roller, or has been sounding rougher than usual lately) you can perform a quick test to determine if you are dealing with a safety sensor problem or a force reversal.
All you do is press and hold the wall button. If the opener will only close your door with the button held down, you can be sure the safety sensors are the source of your problem. Before you try this I recommend reading the details of my procedure to override the safety sensors.
If your door reverses despite the button being held down, it is not a safety sensor problem. It could be any number of mechanical problems with the door or opener, and usually requires a professional to fix.
Check the Aligment
Once you have confirmed that your garage door problem is indeed related to the safety sensors, the first thing to check is alignment. Just follow this simple procedure, and don’t worry it doesn’t require any special tools. You can also check the Overview page for more details on how IR Safety Sensors actually work.
If you are sure that your safety sensors are lined up, the next logical step is to check for problems with the wiring. Make sure you know which wiring configuration (Home Run vs Daisy Chain) you are dealing with to avoid confusion.
If the wiring seems to be good, it is time to start considering that you could be dealing with a sensor that has gone bad, or maybe a faulty circuit board. But wiring problems can be sneaky! It’s not always easy or even possible to find the bad spot, especially if it is buried in the walls or run through an attic space (where it could have been damaged by someone putting stuff on it, accidentally hitting it with a screw through the ceiling drywall, squirrels, etc).
Bad Wiring or a Faulty Sensor?
There is one last test you can use to confirm that your safety sensors and circuit board are still working. This will require you to cut the wire to your safety sensors. Later, you will perform a splice to put it back together, so don’t do this if you don’t have the tools, knowledge, or patience for dealing with wiring connections.
You will remove your safety sensors from their mounting brackets, cut the wire (not too short!), and connect directly to the opener, removing the possibility of bad wiring from the equation. If the eyes light up and let you close the door like normal (you will need to keep them pointed at each other), you have confirmed that your safety sensors are still working and that the problem is with the wiring.