Garage door opener mystery
November 19, 2017 5:29 PM   Subscribe

A neighbor's garage door remote is opening my garage door. I have tried SO MANY things to fix it. Please help!

My neighbor's remote control will open my door. I am not just guessing that this is what's happening, we have tested it. My two controllers do not open his door, even if I go very close to it.

We both have LiftMasters, I have an older one and he has brand new one. Mine is Model 1145, not sure about his model but it was installed this year.

I have remotes with dip switches in them. If I change the code in one of the remotes, then reprogram the ceiling unit to recognize it, my other remote will no longer work (suggesting that I have successfully changed the code, and also that the ceiling unit is only recognizing one code at a time). However even though I have changed the codes several times my neighbor's opener will still open our garage door.

Some LiftMasters have a feature where you hold down the learn button to make it forget all the old codes. Holding down the button is supposed to make the light next to the learn button go out, indicating the codes have been wiped. In our unit holding down the button does not make the light go out. The manual for our unit also does not mention this memory-wiping feature, and my experience with trying to reprogram it suggests that it is only remembering one code at a time (because whenever I change the code in one remote and reprogram, the other remote stops working). I think it is just an old model that is only supposed to retain one code.

I thought maybe our opener was only recognizing a subset of the nine dip switches in our controller, and that maybe I was not actually changing the core subcode that was being recognized (and that would also be part of the code in the neighbor's controller), so I tried changing the dip switches in the middle of the row just to be sure. I also tried changing just the first and last of the nine dip switches and noticed that changing either will make the opener stop working, suggesting that the ceiling unit is using the whole nine-switch code not a smaller subcode.

My neighbor has very kindly offered to let me reprogram all of his openers to try fix the problem later this week if I still can't figure it out, but after all the things I have tried I just don't understand why his opener is still able to open my door, so I am not really even sure reprogramming his controllers will work.

Does anyone have any ideas?
posted by insoluble uncertainty to Home & Garden (9 answers total) 1 user marked this as a favorite
Best answer: Have you tried asking LiftMaster? Do they have a phone number or email address?
posted by andoatnp at 6:25 PM on November 19, 2017 [1 favorite]

I would absolutely start with reprogramming his openers. It is kind of him to allow you to do this, but also a joint issue you both have - he doesn't want his remote to open your garage door, either, and if it keeps opening your garage door it may cause issues in the future (what if someone breaks into your car, or your house while the garage door is open, etc.)

If this doesn't work, I'd replace the circuit board on your garage door (probably $100-200 plus install). The non-optimal nuclear option if that doesn't work (and it really should) is replacing the unit entirely.
posted by arnicae at 6:26 PM on November 19, 2017 [1 favorite]

You can buy a whole new garage door opener on Amazon - with rolling codes and all that good stuff - for less than $150.

And they're not that hard to install. It was one of the first projects I did when I bought my first house.
posted by Hatashran at 7:16 PM on November 19, 2017 [1 favorite]

Just a quick question: have you completely shut off the power to your opener unit for a few minutes, and then turned it back on? Sounds cheesy, I know, but I've had a few openers that have to re-learn rolling codes after a power cycle, so if you power cycle then use your own remote to trigger the first opening, perhaps your neighbor's openers will no longer be allowed access. It is definitely a shot in the dark, though.
posted by davejay at 7:45 PM on November 19, 2017 [1 favorite]

Response by poster: Yes on the power shut off. I try that all the time when I unplug it to keep it closed!

I also forgot to mention that I am a renter, so technically I can try to get maintenance to fix it if it really needs replacing, but it's going to be really annoying to try to schedule them and my neighbor at the same time for testing. (If my neighbor's not around to open it I can't demonstrate that it's still broken. They have been really cooperative, but they don't want to loan me their opener for testing, which is understandable). I would love to be able to fix it myself to avoid the hassle.
posted by insoluble uncertainty at 8:24 PM on November 19, 2017

Best answer: His was installed this year? Did a professional company install it? If so, they should be rectifying the issue (as they should have tested for this during the installation). If it was the handyman or your neighbor himself (someone who isn't a garage door pro) 2nding call Lift Master.
posted by vignettist at 12:00 AM on November 20, 2017

Best answer: Liftmaster contact page. But I would also check with their installer first.
Some things to check before you contact them:
Get both model numbers of the openers and preferably take a picture of the template that should be on the back of the openers.
Does your neighbors opener open yours all of the time, or only sometimes?
I suspect what is happening here is that your opener is set to open with a single frequency or a code on a carrier. That is why you have to change dip switches on both the remote and receiver. Your neighbor's is smarter and will probably need a combination of codes to open. So you might need code 6 but your neighbor needs 634. But yours will open of your neighbors code has any 6 in it. So yours will open with 634, 286, 162, etc....
The other coding option is that his newer opener has a more sensitive receiver, so their can be more codes. So his may need 6.1, but yours will open with 5.8, 5.9, 6.0, 6.1, etc.

I am not sure what the solution may be, but Liftmaster seems to be sofisticated enough that they should be able to blacklist certain codes on your neighbor's receiver.
posted by Short End Of A Wishbone at 4:56 AM on November 20, 2017

Best answer: Does the neighbor's remote open your garage door every time it is activated or only occasionally? It could be that the neighbor's opener is spewing out enough bits that occasionally it matches your garage door.

What I suspect is that your garage opener uses the old system of just a few bits set by dip switches. The new garage opener uses the newer rolling code system. The old system is pretty primitive. It just looks for a sequence of a few bits matching its dip switches, no matter the timing or framing. It is just a simple shift register receiver that accepts any bits coming in and moves the bits sequentially through the shift register. If the pattern in the shift register ever matches the dip switches at any time, it activates the opener.

Your neighbor most likely has the newer rolling code system. This is much more sophisticated and as such may transmit hundreds of bits every time the button is pressed. Some of these bits are the same each time, such as serial number of the remote but others are different each time such as the rolling code and decode key. It is possible that occasionally it may transmit a sequence of bits that matches your code.

So it would be important to know if your neighbor's remote opens your door every time or only occasionally. If occasionally, then it could be random chance given the large number of bits transmitted by the rolling code remote. Your system, with 9 dip switches, has a maximum of only 512 possible codes.

If it opens every time, it might be that your code happens to match a fixed part of the neighor's code. You could experiment with your dip switches to find a code that doesn't match, but that would require getting the neighbor's remote for experimentation. The neighbor's rolling code remote transmits hundreds of bits, some of which are repeated each time and some of which are pseudo-random.

You might be able to experiment with disabling the antenna on your opener. Typically on these older openers, there is an antenna wire dangling outside the opener. You might experiment with removing or shortening that antenna wire so that the opener will detect your remote but not your neighbor's remote at greater distance. It's pretty easy to fiddle with the antenna. If you open the housing of the opener, it will just be a wire attached to a screw terminal. You can remove or shorten it to experiment.
posted by JackFlash at 8:23 AM on November 20, 2017

Response by poster: JackFlash I am pretty sure you are right that the neighbor has the new rolling code system. We definitely have dip switches in our remotes, but I don't see anything in the manual for the ceiling unit about dip switches in there. It just has a "learn" button that you press to copy the code over from the remotes.

I have tried changing our dip switches about 5 times and every single time the neighbor's opener will open it. They have never had a failed attempt.

It also doesn't seem to respond to other neighbor's openers even though we have several other houses nearby, just the one neighbor.

The antenna idea is interesting, but sadly it doesn't actually respond all that well to our own openers. I often have to press the button several times while my neighbor can open it from extremely far away without even pointing their remote very carefully.

Short End Of A Wishbone I think you are probably right that I will have to contact LiftMaster.
posted by insoluble uncertainty at 10:41 AM on November 20, 2017

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