Prius v Antenna XM Satellite Fading

My 2012 v3 has XM radio which I use almost exclusively since I live in the country where hills make the good HD FM stations flaky (although when they work the sound quality and bass are better than satellite).

About 2 weeks ago the XM started fading in and out for no real reason in places where it never faded for 3.5 years since new. Sometimes the fade would be 10 seconds to 15 minutes. FM, AM and all other display audio functions were fine. An XM reset was sent a couple of times with no change.

* See my post #10 below for results after installing a new antenna amplifier base

Has this happened to anyone else?

The antenna base apparently is the $165 unit below part 8696047031.

 

I am pretty sure the sat antenna is on the roof top antenna base. The GPS antenna is under the dash. Aftermarket sat tuners antennas, including some added by dealers particularly on gen 2 vehicles, are often mounted on the right corner of the dash. XM also broadcasts on the FM band for use in big cities where the buildings might block orbiting satelite signals. So in big cities the receiver automatically switches back and forth. In my case the XM FM band also gets weaker.

 

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The fading is getting worse, sometimes 15 minutes at a time! To verify the XM antenna is at the roof, I did a quick experiment and covered the antenna base with foil when it was working on XM; sure enough the XM went away until the foil was removed.

Link with a description of replacing the antenna base on a Gen 2 and inside view of same

 

Update:

The dealer won't fix it until it fails totally because they think trees and clouds can cause dropouts (which I have not had for almost 3 years along the same routes). As stated above the dropouts are sometimes 15 minutes long while I am driving! Give me a break, Toyota dealers (I talked to two different dealers so far).

So I have two game plans:

First I have an old portable XM receiver (XM2go) that I am connecting to the car using a separate magnetic antenna with it's audio wired into the car's AUX jack. I can then check audio with the built in Display Audio XM and with the portable on the road. The portable has an added advantage as it has an "Antenna Aiming" function that allows realtime signal strength of both the satellite and the land based terrestrial transmitters (one in Austin and one in San Antonio in my area, both low power 8kw).

Second I ordered an $11 adapter cable for the Display Audio's XM antenna input (a GT5-1s to SMB Male Bulkhead cable). This, if necessary will allow my $20 portable XM magnetic antenna to plug in to the Display Audio. However this requires pulling the Display Audio unit and running the antenna wiring cleanly to the roof, not the most desired solution.

Meanwhile the existing antenna/cable/head unit problem on XM seems to be getting progressively worse. Maybe it will fail completely.

 

The last two days almost completely out.

 

Probably will do that after the first of year.

 

I finally broke down and fixed it myself using a part from toyotaonlineparts.com. See attached for installation details. There is also a Gen2 thread on replacing the satellite / fm / am antenna amplifier and base, however it's an earlier standard Prius with different connectors. The Prius v is a little more difficult as interior panels must be removed to access the part and it's connectors.

Toyota's repair guide requires a complete removal of the headliner (accessed through a removed windshield!) which I was not about to do. Instead I removed the interior panels from the rear right side of the cargo area to allow detaching the rear right corner of the headliner. I used portions of "INTERIOR PANELS / TRIM: ROOF HEADLINING: REMOVAL; 2012 MY Prius V [06/2011 - ]" from the TIS Toyota resource.

There are at least three versions of the antenna base, one with a satellite equipped head unit, another with safety connect and a third without satellite or safety connect. More info in attached. The dealer or online source (another dealer in my case) can verify the part number with your vin. The new part has a revised number so some improvement in performance or reliability is likely.

* Update March 4 2016
Still working fine. Today Ebay has a used Prius v Antenna Amplifier Base available. Not positive which of the three types this one is but it is significantly less money than new. It looks the same as my pics in attachment below although I can't see the connector ends. The seller's part number is not a valid Toyota number, but simply a different stamped on housing number. I might be concerned if it were not the updated/revised part I installed (mine now has the superseded part number over what was factory installed) but I would have considered buying it with the ebay seller's 14 day return policy.
12 13 14 15 Toyota Prius V Roof Radio Antenna M | eBay

 

Yes it did fix the problem. I added an attachment in post 10 above and a few other points. With a proper antenna amplifier, my drop outs only happen when beneath an underpass for more than 4 seconds (buffer) or in an enclosed garage. Even then, big cities have landbased "fm" xm simulcasts which will work inside garages.

 

Maybe yes maybe no on a failing antenna amplifier. My old one usually worked in clear blue sky with no trees in sight. The antenna base's rf amp ensures a good signal in rainstorms, trees, etc and drives a pretty long cable from the back to the front. Same strategy employed on satellite tv, free tv hdtv roof antennas and our vehicles.

 

XM uses different bit rates (and therefore quality) on different channels. Talk channels have the worse quality while classical might have close to the best. A lot of this happened when Sirius was allowed to merge with XM. FM broadcast in HD is clearly superior to XM or standard FM, assuming you are listening to the first HD channel per frequency as the second and third are mono and low bit rate. Standard FM can sound good with a good signal, but not as good as HD. The problem with our "display audio" car radios is a lack of Digital Sound Processing (even though it says DSP for auto volume). Car radios have always provided rock, jazz, classical, etc profiles that would selectively boost certain frequency ranges and we are used to having that (sometimes as simple as "bass boost"). Display Audio does not have it, combined with poor placement of the rear speakers and speaker quality in general. With that said, a good HD FM signal blows away a good XM bitrate which is better than standard FM.

Some people have never heard good HD FM on their Display Audios and are pleasantly surprised when they do, particularly on music with wide frequency response requirements. Find a strong rock station in HD, turn it up, then use the HD soft button to toggle back to standard FM.