Introduction: Garage Door Does Not Close

Picture of Garage Door Does Not Close

It was late in the evening.  My wife had just come home.  The garage door did not want to close when she pressed the button on the remote.  It had worked just fine a few hours earlier.  My tools are in the garage.  Leaving it open all night is not an option.  

Step 1: Force It to Close?

Picture of Force It to Close?

This is the hard wired switch on the wall.  She was able to make it close by holding the pressure plate on the switch down until it had closed.

Step 2: Signs to Observe

Picture of Signs to Observe

The light on the ceiling mounted opener flashed as she held the wall switch down to close the door.  That is not normal.  

Step 3: The Sensors

Picture of The Sensors

This is one of the sensors.  There are two.  One sends a beam of infra-red light to the other.  If anything interrupts this beam of light, the garage door will not close and the ceiling light on the opener mechanism will flash as mentioned in the previous step.  This is, of course, a safety feature to prevent the heavy garage door crushing anyone or anything that might be in the pathway of the door when it comes down.  Check to be sure no child's toy or anything else blocks the path for the infra-red light beam.

The text box feature would not save when I did this Instructable, so I am overlaying colored arrows as keys to my explanation.  

Most garage door problems can be traced to the sensors.  The circuitry inside the sensors is quite reliable and has a long life.  The first thing to check is the mounting brackets (blue arrow).  Did something bend them so the sensors are no longer aligned?  A quick visual inspection of each should be sufficient.  In doubtful cases, you can stretch a long string between the sensors to see better if they are aligned. 

The red arrow points to the LED.  Each sensor has an LED.  It should be bright and show a solid color.  Some are green and some are red, depending on the manufacturer of your opener unit.  One sensor on our unit showed a bright steady LED.  The other, this one, was weak and it fluttered rapidly.  That, together with the flashing ceiling light and the need to hold the switch button, are signs something is not right.

The yellow arrow points to the lens.  It should be clean on both sensors.  This garage is my workshop.  It is always possible sawdust could have accumulated on the lenses.  As a precaution, wipe them with a rag or a tissue.

The green arrow points to the wire that runs between the sensor and the opener unit on the ceiling.  Look for obvious physical damage (bare wires, loose connection, cut or broken wire, etc.)

Step 4: What, Exactly, Could Be the Problem?

Picture of What, Exactly, Could Be the Problem?

We do have a manual for our opener unit, but its troubleshooting section tells you how to check a few basic things, and then says, "You may need to call a technician for repair service."  I am not much in the mood to wait for a technician at the time I want to be going to bed, if I can find one who will come late in the evening.

It has been two years since I had problems with a garage door opener, and that was a different unit than this one.  I forget the procedure for troubleshooting one of these units.  I have come to go on-line for help on the occasions when the garage door opener fails to work.  After a quick search for "garage door opener troubleshooting," I opened this page.  There are some general help pages, but they do not offer much more assistance than our manual and its suggestion to call a technician after checking a few basic things like obstructions to the infra-red beam and power to the circuit.  

Help suggestions are often very brand specific.  The image with this step is a chart for diagnosing problems with the sensors on a Genie garage door opener.  Look closely and you can see that Genie gives diagnostic clues and codes in how many times the LEDs flash and in the color of the LED that shows something unusual.  Our unit is not a Genie, but a Liftmaster.  The help sections for Liftmaster units are more general and not very helpful.  

Step 5: The Solution

Picture of The Solution

I know from past experiences that the electrical connections to the sensor must be good, or the door opener does not work properly.  I had already checked for obstructions to the infra-red beam, for power to the system, cleaned the lenses on the sensors, checked for alignment of the sensors by looking for bent brackets and so on.  I grasped the small plastic plug at the end of the wire and pulled it out of its socket on the sensor.  It required quite a strong pull.  Do not pull on the wire, but on the plug.  It may seem there is a catch that must be released first, but there is not.  When I put the plug back into its socket, the LED no longer fluttered and the garage door worked properly once again.  In time these connections corrode slightly with oxidation.  Breaking and making the connection again is enough to restore its function.  And, I did not need to call a technician.  


adidame (author)2017-11-09

Thank you for posting!

Phil B (author)adidame2017-11-09

Thank you for looking. Actually I have a very selfish motive. The next time I have a problem I can refer to my Instructable without doing all of the research again. It is also fun to benefit others now and then.

ChristopherP230 (author)2017-09-09

We have a large 8' wooden garage door opener with a new Chamberlain opener and the sensors are fine and alligned, but the door opens fine but it will not close? I've tried incresing the power to the down control and still will not close. It gets to a certain point and stops and when you press the button again it goes up and this cycle continues. Please assit if filmiar

Phil B (author)ChristopherP2302017-09-09

I do not regularly repair garage door opener systems, and can go a number of years between troubleshooting problems with one. When you say yours is new, does that mean it is freshly installed and not working, or does that mean it had been working, but now will not go down? I am guessing the door encounters some form of resistance it interprets as an obstacle it should not crush and it stops. Is something binding? Can you operate the door smoothly by hand when it is released from the opener linkage? While the door is released from the opener linkage does the linkage travel across its normal full range? Those are some things I would check.

NinjaDude (author)2016-08-05

Thanks! Your instruct able made me look like a smart guy. I only wish I had made it seem like an all day job. I finished this in record time, then had to do more on my honeydew list.

Phil B (author)NinjaDude2016-08-05

Garage door problems are temporal and finite. Honey dew lists are eternal and infinite. I am glad it was helpful. Thank you for the report back.

Eclipse2975 (author)2016-07-24

Very informative article. I do have a question for Phil. I have Chamberlain LiftMaster. One of the sensors is not on. Doesn't look like wires can't be unplugged. Should I replace entire sensor? If so should I replace a pair? Thank you

Phil B (author)Eclipse29752016-07-25

I am not a professional garage door opener serviceman. The opener on the garage featured in the Instructable is a LiftMaster, and the wire connections to the sensors oxidized so that there was a poor connection. Can yu use a sharp knife to wiggle the very small plug on the wire from its socket in the sensors?

GuaysheenE (author)2016-06-20

Thank you sooooo much! I had the same problem and after following your clear instruction. It works!! My garage door opener is working properly now. The problem was the two sensors didn't line up.

Phil B (author)GuaysheenE2016-06-20

Thank you for your report. I am glad it was helpful.

BettyJ6 (author)2015-10-02

That is a tough situation since no one wants to leave their stuff unprotected with the door open. I wonder if there was something blocking the beam at the opening? That would make it so it wouldn't want to close. Checking the springs might be a good idea as well.

JohnS265 (author)2015-09-28

I have a garage door safety beam that blinks when blocked. The garage door rarely works with any button. I checked wires and cleaned the lenses. Any other ideas?

Phil B (author)JohnS2652015-09-29

I have had problems with the alignment of the beam and its receiver from one side to the other of the garage door opening, especially if something bumped it. A long piece of string pulled taught to follow the beam's actual path can be helpful. I also have a laser pointer on a 24 inch household carpenter's level. It is useful for checking up and down as well as left vs. right deflection on the beam. The other problem I have had is making sure the remote and the main unit are programmed to the same code. Rubberized buttons on remotes sometimes lose the conductive coating on the working side and do not make good electrical contact. Of course, the batteries in the remote need to be good. Most problems are due to small things rather than major failures.

HerryW (author)2015-03-30

Nice blog. This is great collection of helpful tips for garage door maintenance and I think everyone can easily use these tips in order to maintain his/her garage door without the need of any professional. I think everyone should read this blog once and apply these tips by itself. If you want more Information visit

eoneill137 (author)2015-02-04

thanks! Turns out I had this exact problem (and model door opener). Sure enough, removed and re-connected the connector to the sensor, and viola! working door.

Phil B (author)eoneill1372015-02-04

Congratulations to you! I am glad this was helpful to you. Thank you for looking.

johng652 (author)2015-01-08

Well I have two comments. Great way to show how a simple problem ( corroded / broken contacts ) could and often does lead to calling a technician. But with just a little digging that expense can be avoided. To prevent corrosion in the future you may want to use a dielectric grease on those contacts. Second is I noticed in your response that when the emergency release was used the door was impossible for you to open. This is a problem. The springs should counter the downward force of the door so that a person can open it unassisted. By making sure this is done you reduce the work load the opener has to do. From a safety point the garage can be opened even though no power is available. A fire can knock out power real easy. I'd call a highly rated garage door service and get this fixed. It does not matter what material the door is made of the springs/ counterbalance system should do this job.

benneewilles (author)2013-04-05

Why don't you try to reprogram it??
This might help you with your garage door opener

Phil B (author)benneewilles2013-04-05

The problem turned out to be an oxidized electrical connection. Reprogramming would not have helped. Thank you for looking and for commenting.

garagepro (author)2012-02-29

The problem that you have is a commend problem. and it's easy to fix it. You problem just need to adjust the sensors. And to make sure that both the lights are turned on. If that don't work and you need more help you and found the manual instruction in this web site.

Phil B (author)garagepro2012-02-29

I appreciate your information. If you look again at step 3 in this Instructable, you see I noted the LED on one sensor unit was bright, but the other fluttered weakly. In the last step you will notice that the reason for the weak and fluttering LED on one of the sensors was due to an oxidized connection where the control wires attach to the sensor.

Tim Temple (author)2011-12-15

The instructions on my garage door say that entropy makes the door stiffer to pull up or down. The motor detects that as a problem and stops the door. Especially when it is getting cool.

Make sure nothing is breaking the electric eye. Disconnect the door from the opener with the lanyard. If the opener operates okay, look for two rheostats on the back of the motor -- one marked "up" and the other marked "down." Give the appropriate rheostat a slight clockwise turn and actuate the opener to reconnect it. That should solve the problem.

nwait (author)2011-11-13

Hi PhilB

I'm not sure if my comment is in any way related to your problem, but might spare you some hassle later on.
Reading your statement that the door was too heavy and you couldn't let it down manually, means that your torsion springs are unbalanced. This also means that the door is also extremely "heavy" to open. All this relates to excessive loads on the garage door opener, which then can make it register an 'obstruction', making it either return open while closing, or remaining in a half open state while going up.
I suggest you have it seen too, so next time you encounter a contact problem you will be able to operate the door by hand. Easily, as it should be....- Remember, the door opener is there for convenience, not to operate as a weightlifter for faulty balanced doors. This is also unsafe.
Norman - Garage door installer - South Africa

Phil B (author)nwait2011-11-13


Thank you for your comment and the information. Not many years ago one of the springs broke. We had professional service personnel replace the broken spring. I would have thought they would have adjusted the springs properly. Is it possible they did not?

nwait (author)Phil B2011-11-14

Hi Phil

Yes it's possible for them to either have "underwound" the spring, installed the wrong spring in terms of weight to height ratio - springs are manufactured according to the door's weight and opening height ie. lets say your door weigh approx. 160 Kg's, then you would probably have on 2x springs of 90 kg ratio each to lift it up to 2.1m high door opening - this is so that the cables remain taught at opening height and not come off the drums because off becoming too slack. The other factor is that doors need servicing once a year. Springs loose tension as they are under strain while the door are closed, which it is 90% of the time - on average. this means that 90% of it's lifespan it's standing and loosening tension gradually. This needs to be adapted/tightened/serviced yearly. Over progression of time the springs become weak and are unable too lift the door.
Hope this helps.

Phil B (author)nwait2011-11-14


Thank you. We should probably have the service guys out again. It has been more than a year, for certain.

Poolshark152006 (author)2011-04-03

You do realize that you are able to Open and Close the door manually by pulling the red string buy the garage door motor...

Phil B (author)Poolshark1520062011-04-03

I know about the red emergency release. I did pull the emergency release and quickly learned that this old wood door is so heavy and so heavily sprung that I would have needed several large helpers to bring it down and close it. Your suggestion might work well with a modern fiberglass and aluminum door. But, doing that still does not solve the problem of why the sensors would not let the door opener work. Service calls by garage door technicians are quite expensive, especially after hours. It is much better if a homeowner can follow a simple procedure like I outlined to troubleshoot the sensors and restore function in a relatively short period of time.

Poolshark152006 (author)Phil B2011-04-03

My response thought was you would be able to pull down for the night, then fix it in the morning...

Phil B (author)Poolshark1520062011-04-03

Thank you for the suggestion, but this door is too heavy. I would have needed a couple of guys to help. At least my wife did get it down by holding the switch.

rimar2000 (author)2011-04-01

Bravo, Phil. Most electronic and electrical failures are due to problems of contacts, especially in areas of low voltage circuit. My microwave oven has over 15 years, and I had to gut it twice to clean the contacts. It's amazing how always something rust, or sulfate, or dirty.

Phil B (author)rimar20002011-04-01

Many home mechanics do not work on their own automobiles now because of the computer controls. But, as a professional mechanic on the radio stated, "Cars today still need air, fuel, compression, and spark." He encouraged home mechanics not to worry about the computer circuits, but to check the basic things that have always been important and are little or no different than before computers. One thing that could be added to that would be checking electrical contacts and connections for looseness or corrosion.

I was surprised that nothing was said in the helps for diagnosing a garage door opener problem about oxidation on contacts between the sensor and the wires leading to it.

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Bio: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying ... More »
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