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2014 Forester CVT
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8 Posts
Discussion Starter · #1 · (Edited)
About two months after I got my 2014 Subaru Forester, I noticed that my garage door opener (i.e., its remote control) was no longer working reliably. I replaced the battery, but that didn't help.

I then noticed more specifically that:
- The first time pulling out of my garage in the morning, I had to wait about a minute before the opener would work.
- The second time pulling out that day, I had to wait only about 20 seconds.
- Third and subsequent times that day, the remote worked correctly the first time.

I then thought that the car's Bluetooth connection to my phone might be interfering with the opener. (Previous to this car, my phone had a Bluetooth connection to a GPS. I have turned off the Bluetooth on the GPS.) But Bluetooth uses a frequency near 2400 MHz, whereas coded garage door openers use a 300-400 MHz frequency.

So what in the Subaru Forester uses that same 300-400MHz band? Well, TPMS uses 315MHz. I now suspect that this is the source of the interference. Unfortunately, I see no reasonable solution to the problem.

I have found a thread in another forum (for the Ford Focus) describing exactly the same problem, with evidence that TPMS was the source of the interference. He, too, originally suspected Bluetooth, so his original thread title turned out to be wrong.

Sync interferes with Garage Door Opener - Page 2
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For some strange reason, the TPMS system stopped communicating with the OEM wheels in the basement. I now get a "System Fault" every time I start the car. AND poof -- the garage door opener has been working like it should -- inside the car -- with the car running. Further confirms my theory as the source of interference.
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Here is a post from yet another forum about interference with Craftsman garage door openers, which just happen to use the exact same 315Mhz frequency as TPMS!

http://www.diyforums.net/craftsman-garage-door-opener-4374924.html
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Sears refuses to fix, but acknowledged that the problem is caused by rf interference with their 315 mhz frequency use by motion sensors, etc... They insist that the frequncy change was mandated by the FCC. They will not post the possibility of rf interference with their openers on a web site or any advertisement. They will not post it in their stores, and they do not advise their sales people. Both Sears and Chamberlain also will not and have not put this information in any instruction manual, nor do they have any fix. I took off and threw out a motion sensor on my light and initially fixed the problem. This past month I recently installed a water fountain bird bath with six small LED lights in a front garden, which I found again shut down my remotes AND my home links in my cars.
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2010 Forester 2.5X
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1,692 Posts
Yes, but....
Isn't the TPMS in your wheels asleep when wheels are not rotating...?
Isn't it a receiver only that takes the signal from your sleeping tires?
What about your rearview mirror.. have you set up that to open the garage door?
 

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1999 Forester 5MT
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856 Posts
The sensors may be asleep when they're not rotating (aka, not transmitting their pressure data), but they're not in hibernation either. Upon startup, the TPMS controller should ping the sensors as part of a system test to verify their presence and operability. Once they detect rotation, they will begin feeding pressure data.
 

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2008 Forester X Premium 5MT
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8,064 Posts
No issues here. 2 Craftsman/Chamberlin openers and two '08 Foresters both with TPMS. Never had an issue.

Openers and TPMS are all 315mhz.

Craftsman DC Belt Drive Garage Door Opener with DieHard Battery Back-Up

The old 390mhz frequency that many companies used was and is reserved for Department of Defense, They(380 - 399 mhz) have been reserved for the DoD and law enforcement since WWII. Really they should have never been used for openers. Now that the DoD and law enforcement are starting to use these frequencies the FCC is enforcing the policy. Thus the over crowding in other frequencies now.

My Keyless entry wont work when the cart boys at the local grocery store are using the wireless remote for the cart pusher. I have to wait until they stop or get out of range.

http://www.thestate.com/2013/06/14/2818602/fort-jackson-frequency-change.html

http://www.wjbf.com/story/22551791/...at-fort-gordon-may-affect-garage-door-openers
 

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2014 Forester 2.5i 6 spd
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433 Posts
Read this out of boredom. That a transmitter can interfere with keyless entry suggests use as an anti-theft device.:huh:
 

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2008 Forester AE
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1,723 Posts
My Keyless entry wont work when the cart boys at the local grocery store are using the wireless remote for the cart pusher. I have to wait until they stop or get out of range.
Haha, mine as well, I always give the cart guys dirty looks- :Banane35:
 

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144 Posts
I think it's very unlikely that the TPMS would interfere with anything. The reason is that TPMS is "off" most of the time, and only transmits very briefly. Depending on the car, it can be once a minute or once every 5 mins, or so. The actual transmission is very short, only few milliseconds. Actually, out of curiosity I have been "listening" to my TPMS (in a Toyota) using my ham handheld tuned to 314.98 MHz. I can clearly "hear" the TPMS few seconds after starting the car up, and then every five minutes when the car is stopped, and once a minute if it's rolling. In all cases, the actual transmission is just a barely perceptible "click". This leaves plenty of time "free" for the door remote to work. The probability that the two transmission would overlap is very small, considering how short TPMS data transfer is, and the "idle" period between transmissions. Even if the happen to overlap, pressing the remote button again just a second later would result is a "clear" signal.
 

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2010 2.5X Limited 4-speed Auto
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1,979 Posts
It sounds like you may have an older analog garage door opener. We had a similar problem in my office's garage with the opener getting false opening signals from one of the vehicles. We installed a new digital encoded opener and the problem disappeared.
 

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2014 Forester CVT
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8 Posts
Discussion Starter · #10 ·
I think I have figured out, and resolved, the problem. It was not the car's TPMS, but rather the LED light bulb I installed in the garage door opener. Internet reports indicate that these new bulbs can emit a large amount of radio noise that can interfere with all sorts of wireless devices.

I replaced the LED light bulb with an old incandescent bulb, and my problem went away.

You may ask, Why was I so foolish as to install a newfangled LED light bulb in my garage door opener? Because I was trying to save money on electricity; and because no commonly sold CFL bulb will fit into my garage door opener's bulb receptacle, which is very restrictively shaped.

I guess I'll have a major problem in 2020, when the United States phases out incandescent bulbs.
 
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