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2018 Cell Tower Interfering with XM Radio. Filter Fix

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Since I bought my 2018 Premier 5 years ago I have noticed that when near certain cell towers, my XM radio signal is lost. This only affects some channels, ie channel 25 no problem, channels 111 or 125 XM audio muted. I have never complained about this until now -- as more towers are raised, the problem occurs more often!
I have recently learned that XM radio and T-Mobile have been arguing their cases to the FCC since before 2015!?! I have found that XM has a filter for this problem, but only for the 2016-2017 Volt?
Interestingly they have not advised Volt owners of the problem or possible repair, but keep taking our monthly subscription fee.

I have found GM in fact had issued 2 service bulletins concerning the issue -- 16-NA-356 and 19-NA-081! This covers multiple Chevy models and years, but for some reason only mentions 2016-2017 Volt. It mentions installation of a SXM filter, part number 84601829. I have spoken with Chevy parts locally and they had no info on that part other than it is a filter. The info about the part in the service bulletin looks as though it would also be compatible with my 2018 Volt!

Has anyone had any experience with this issue?

Does anyone know where the antenna coax connects to the XM radio for the 2018 Volt? How hard is it to access?

Thanks, in advance!
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Were the TSB's issued prior to 2018?

My guess is the solution will work on your 2018
 

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Discussion Starter · #3 ·
The TSB was written in 2019. I have spoken with my Chevy dealer. They can get the $4.00 part. With installation the price is over $325! Oh, and of course no guarantee it will fix the muting!

So does anyone know how hard it is to get to the back of the XM radio module? As I understand it, installation is just unplugging the antenna and plugging filter into module, then antenna into filter.....
 

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Discussion Starter · #4 ·
Well after numerous calls with SiriusXM, they are sending me their SXM filter which is compatible with the 2016 Volt. It comes with an "install card" which provides free installation by an "installernet" member installer. I am looking forward to finding out who in the area will accept this job AND then will have to decide if I am OK with a non-dealer working on the car!

Who would you guys/gals be comfortable with accessing your Volt's radio to install a filter between the antenna coax plug and XM radio module?
 

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Sure. They take apart dashboards all the time. And the Volt is not really all that special there.
It's easy to forget that most of the Volt is pretty much the same as any other car. You don't need a Volt specialist to work on seats, shocks, brakes, windows, body, engine, etc.
 

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The filter must be an inline notch filter. XM is in the 2.4GHz area while some 5G is at 2.5GHz. I ran into a similar problem with airplane altimeter radar interfering with a digital syndicated radio station feed we got from a 10ft C-band dish on a roof. We got program dropouts when the planes came into land from a certain direction. It took a spectrum analyzer to figure it out as few were aware of the problem. Most stations had their dishes ground mounted where the trees and buildings blocked the interference.
 

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Discussion Starter · #8 ·
FIXED FREE TO ME! After numerous calls to Sirius XM, the company sent me a filter and install card (payment for installation) that they insisted was only applicable to 2016 Volts. Today I had the $4 part installed and cell phone towers no longer interfere with my XM radio.

The installation took an hour BECAUSE all the data on location of the XM module (that the installer had access to) was incorrect. Initially they pulled apart the front dash looking for the radio. Be aware that on the 2018 Chevy Volt Premier, the XM module is located below the subwoofer, passenger side rear if car! The actual replacement took no more than 30 minutes -- Chevy wanted $318! Also of interest -- the filter supplied by SiriusXM has the same part number as the Chevy number (84601829). Will try to attach two photos.
Motor vehicle Automotive tire Automotive exterior Hood Bumper
Fluid Gas Cable Wire Electronic component
 

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Super interesting. A little over a year ago, I was convinced the XM antenna was failing in my 2017. For almost a month, I would get long silence/fuzz while driving. Poof, it went away. No apparent rhyme or reason. It has started doing it again recently, although the pauses are much shorter. The dealer wanted to sell me a new XM antenna for ~$800 installed because "they all fail and we do a lot of those." Well it clearly wasn't the antenna (yet, at least).

There IS a lot of new development in my area, including a couple cell towers that went up in the past couple years. Hmm..
 

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Discussion Starter · #10 ·
Easy to know for sure. It only affects some channels. Next time your XM mutes within a mile of a tower, switch to CH25. If it works OK but another channel does not, installing a $4 Filter will fix it! Good luck.
 

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Easy to know for sure. It only affects some channels. Next time your XM mutes within a mile of a tower, switch to CH25. If it works OK but another channel does not, installing a $4 Filter will fix it! Good luck.
I also have 2018 LT. I recently experienced "Signal may be blocked" the goes to searching for XM or something like that over the last week. While I had that message I could not the to any channel, like Channel 1 to test signal. I call SiriusXM and they went through troubleshooting including turning Volt off and opening the car door for 30 second. They sent refresh signal and and the signal came back but it was flakey and cuttinging and out. Finally after a short drive maybe 1/2 mile all was good. But today after starting out for short drive it was deja vu...back to signal may be blocked.

when I talked to technician today he said take it to dealer? think this would be covered by my CPO extended warranty>

Could this be that same problem? How did you convince SiriusXM to give you the filter and installation?
 

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Discussion Starter · #12 · (Edited)
I also have 2018 LT. I recently experienced "Signal may be blocked" the goes to searching for XM or something like that over the last week. While I had that message I could not the to any channel, like Channel 1 to test signal. I call SiriusXM and they went through troubleshooting including turning Volt off and opening the car door for 30 second. They sent refresh signal and and the signal came back but it was flakey and cuttinging and out. Finally after a short drive maybe 1/2 mile all was good. But today after starting out for short drive it was deja vu...back to signal may be blocked.

when I talked to technician today he said take it to dealer? think this would be covered by my CPO extended warranty>

Could this be that same problem? How did you convince SiriusXM to give you the filter and installation?
If you get signal may be blocked message, it is CLEARLY a different issue. Either you have a faulty antenna, or poor connection between the XM radio and the antenna, or a faulty radio (IMO). Those should be covered by your 36 month bumper to bumper warranty ( I believe) but I know nothing about extended warranties. installation of the XM filter if needed. The filter fixes a very specific problem caused by T-Mobile transmissions interfering with a few satellite channels. Good luck! (If Chevy works on your car under warranty to fix your problem, try to insist they install the filter (part #84601828) too.
 

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I talked to technician today he said take it to dealer?
The XM antenna on another car of ours went bad, so it isn't unheard of to have other problems with the XM system. Your problem doesn't seem to be the same as this thread.

-Charlie
 

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The XM antenna on another car of ours went bad, so it isn't unheard of to have other problems with the XM system. Your problem doesn't seem to be the same as this thread.

-Charlie
Thanks for the reply. Going to dealership next week. Hope my CPO warranty covers it, other wise I pay $$$ for diagnostics. If not fixed then XM gets cancelled. AM/FM still works.
 
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