Weak FM radio reception in 2010 Prius?

No one on here seems to have discovered a Prius with a diversity system, me being in the UK doesn't change this. If you want evidence, then take a look at the threads here where folk have changed head units (as I've done, twice now) and check the photos. All of the pictures seem to show just a single antenna cable, with an ordinary coax plug on the end. Some EU versions (including mine) do have an antenna connector that has the provision for two feeds (with no evidence they are used, just a single cable is fitted), but North American models have a single socket only.

This thread at the top of this section has some details and photos of the back of units: http://priuschat.com/forums/gen-iii...-toyota-prius-model-ii-head-unit-upgrade.html

There are a lot of folk here who have taken the stock head unit out and posted what they've found on here. It's worth taking a look at those install threads as they pretty much prove that the diversity system doesn't seem to be fitted in practice.

I wish they had done this, as it would probably fix the major part of the problem. Those of us who have done some EMI testing on the car have found that it's not a major issue, but the broadband noise level in the VHF band is elevated when the power systems are on. They are within the limits required for EMC approval, but still enough to impact on reception when the desired signal level is low.

Jeremy

 

The thread started well over a year before Toyota issued its first TSB (not coincidently for the more expensive JBL radio). They clearly know about the issue with the stock radio - when/if a TSB comes out? Who knows.

They clearly are not in a rush to deal with things that cost the company - but are not safety related...

 

Not really positive - but quite sure I used a company that supplied us with a diversity antenna for cellular radio - which had a 'single' connection point. Meaning the antenna itself was basically two antennae in one housing. Not to convolute a very convoluted thread....

 

How did you measure EMI? To which standard are you citing for approval? What test equipment did you use? How much is the signal to noise ratio affected when power systems are on in db? Has anyone measured loss in the cabling system using a network analyzer (magnitude and phase?). I just did a google search on the sight and saw no reference to RF Network Analyzer so I can safely assume that no one has checked the signal path. I also don't see any reference to signal analysis measurements done at the input to the radio. To say that switching the car on and off and the FM reception gets worse is one thing. To say that the displayed noise level on a spectrum analyzer goes up by this many db when the car is turned on or that harmonic distortion increases by this many db or signal to noise ratio decreases by this many db means something to a Toyota design engineer. Anecdotal evidence from cars parked in fringe areas does not. So what I have seen in these 50 pages of discussion are indications of trial and error, and component swapping but not a single RF measurement. I know that a lot of us are RF/MW guys and some must have access to this equipment one way or another so maybe somebody ought to call their Agilent salesguy and borrow a spectrum analyzer, download the EMI software from their website and get to work. Then borrow a 75 ohm ENA and characterize the signal path. Until then the next 50 pages will be more of the same conjecture and Toyota engineers would do well to ignore the complaining. I'd do it but I retired last year and play too much golf. And when I get flup on my FM stations, I just switch to XM.

 

Jeremy, thanks for that link to the .pdf of the install job. It does in fact picture a single coaxial cable for the antenna. Of course, that doesn't rule out the existence of another, unused cable somewhere, but it strongly suggests there isn't one. I'm still unclear why Toyota has made so many references to the "diversity antenna," unless they are (mis-) using the term to refer to the antenna having both FM and XM capability, an egregious error that should certainly have been caught by technical review.

I too would be interested in seeing some objective test measurements of the RF environment, as I've personally not experienced any noise of any kind that was not obvious multipath distortion. It's possible the real culprit is an RF stage that is set "too sensitive" in the FM receiver module, coupled with a complex RF environment that "confuses" the detector through multiple, spurious signals. That combination could produce the near constant multipath distortion evident in the factory II radio. I may try inserting a few db of attenuation inline with the antenna, if I ever take the dash apart. That could help. It's also possible there is an outboard antenna amplifier in that module on top of the car - seems I read about that - anyone confirm? - and that, too, could spell trouble.

Edit: another quick note - Jeremy, I'm not noticing any additional problem with "low signal levels." The receiver performs equally poorly with all signal levels. That is, the problem is just as bad, if not worse, when I should be getting "full quieting" in town. That confirms, for me, the diagnosis of multipath distortion.

 

I think Toyota should find a fix for the vehicles that are already out here with poor reception. They should not just make a fix for the future, after all we paid for a radio that would perform as it was suppose to! It is terrible!

 

I think the best thing that can be done is to see how many db can be gained in the signal path. That will certainly make reception better in fringe areas.

What is the antenna gain of the antenna?
Is there an LNA between the antenna and the radio? If so what is its noise figure, return loss and harmonic distirtion? What is the insertion loss and return loss in the cables and connectors?
There is not a lot that can be done about receiver sensitivity other than putting in a different radio, but it would be great to know the receiver sensitivity specs of the radio that's in there now. No sense putting in one that has worse specs.
I'm not taking my car apart but there are a lot of you that do. Measure the cable/antenna/lna system for loss, replace cables with better cables, lna's and connectors with lna's with better noise figure and cables and connectors with better return and insertion loss, and try an antenna with better gain specs and see how it affects the response of the system from the antenna to the radio. This is the only way that you are going to increase performance and get better signal to noise ratio at the FM receiver in the radio. There's nothing we can do about the various types of noise generated by the various systems in the car unless you have access to an anechoic chamber and EMI test system and even if you did, you can't modify the shielding in the car without making major changes to the car's electronics and their enclosures. Since EMI is being blamed for phantom acceleration issues, you can bet the new EMI test facility in Ann Arbor will be put to good use to resolve those problems and maybe broadband noise and other EMI issues that may affect the FM radio will be resolved in the process. I'll be interested to see if any measurements get done to take this discussion to the next level.

 

-That TBS is T-SB-0207-10 REV 1 July 29, 2010
Poor FM radio reception
Must check your VIN to see if you qualify.
Radio ID A51882 JBL without NAV
E7022 JBL with NAV
There are three plants involved
Good luck
jim

 

The measurements I made were a bit crude, but nevertheless I believe they were valid as an indicator of the probable causes of this problem.

Firstly, I borrowed a B&K EMC receiver, with the bandwidth set to 200kHz and hooked up a sniffer antenna centred on 100MHz (just because that was all I could borrow). The antenna was fitted to a GRP pole, so that I could stand back and make some rough measurements.

The initial tests were done out in the open, in an area well-known for having a poor FM signal and a generally low background RF noise level in band II. These are reported in this thread in part, they were the tests where I discovered the odd behaviour with the windscreen wipers and the change in the background noise level between power on and off. These initial tests indicated the presence of a raised, fairly broad band (within the limitations of the spectral display attached to the receiver) noise floor when the car was switched to "ready", and so I arranged to "borrow" the use of a large screend EMC chamber for some further tests.

The screened chamber wasn't ideal, as the exhaust extraction system wouldn't hook up to the Prius and I only had a very limited amount of time to do some basic tests. This meant that I wasn't able to use the normal full hemispherical broadband emissions scan system, both because I wasn't able to programme the system to make automatic measurements using the pivoting mesurement antenna boom and because some of the equipment was down for calibration (which was the reason I was able to scrounge access to the chamber). I used the same B&K receiver, in stand-alone mode, because I wasn't able to hook it up to the chamber's IEEE bus to record data and drive the receiver. I basically repeated the ad hoc tests that I did out in the open and got similar results. Broadband noise in the 95 to 105MHz band was around 6 to 8 dB above the background when the car was turned on. The background noise was essentially mush, with no obvious spectral lines indicating a particular interfering frequency. I must stress that this was a fairly crude measurement and that the noise levels I was looking at were below the noise floor of the HP network analyser I tried to hook up (not surprising, as I didn't have a decent low noise preamp to improve the inherently poor noise performance of the NA when hooked up directly to a low gain, wideband reference antenna).

Overall, my thoughts are that the car's systems are a significant contributor to this problem. It's not the only cause; it's very clear that the radio responds poorly to multipath, which is one reason that changing the radio makes the noise less objectionable. However, the fact that the noise floor is elevated by broadband interference from the car is, in my opinion, a contributory factor. I firmly believe that this is why there hasn't been a quick and easy fix for anyone that lives in an area where the FM signal isn't particularly good.

Changing the radio (I've changed mine for two different makes) doesn't fix the problem, although it does make it less noticeable. In my case, the second radio change was to a Kenwood that I had fitted to my previous car, where it received a superb FM signal in areas where it's now unlistenable in the Prius. I've tried all the usual suspects reported on here, changing the antenna, ensuring the antenna amp is working OK, adding a high pass filter into the antenna lead to try and reduce the amplitude of the (pretty high) HF noise that the antenna picks up from the car (my thinking was that this might be blocking the radio). None of these things made an appreciable difference.

Toyota aren't interested in the problem, in my view it's because they know full well what the cause is and know that it's not cost effective to fix it.

Jeremy

 

Jeremy, I agree with you.
I personally gave up. I will send another email to the Toyota Customer care to remind them that they have sold me a car with a faulty radio design that doesn't work and see what they will answer.

Is this a "defeat"? for me and the EU, sure, since I cannot sue directly Toyota and I honestly feel "alone" in this. I honestly did not go deeper in this due to time and because I know how these things go in EU/Germany...they also tend to be expensive (lawyers and the such, and if you are considered guilty....I don't have the money for this).
As for the US, you should sue Toyota in case you have indisputable proof that the radio is not working properly (have luck with that...). I mean, they have been sued for less. But a faulty radio is not a safety thing.
One thing for sure, when I will have to change my Prius, if I am going to get a new Toyota (or any other car for that matter) I will test their radio and if I get the same crap and I am going to the same dealer to buy my new car, I will demand an additional discount on the purchase price! Fool me once, shame on you, fool me twice, shame on me.

This is one of those situations in which the "corporation" can actually get by, by doing nothing. A radio is a 2-500€ device that in the grand-scheme of things (and costs) is not worth for them and for the user to get fixed. And in a court it would be really difficult to show without a shadow of doubt that the radio "doesn't work". It does work, but not to somebody's (us) "liking". And "liking" is not a a thing a EU judge is going to have Toyota do anything about it (actually I cannot sue Toyota in EU, I can only sue the dealer since he is legally responsible of the quality of the car - it needs then to sue Toyota for providing him with a faulty car...) - there are probably in EU very few complains, if any, except mine likely.... , considering also the few Priuses sold here, and a judge as way more on its plate normally that a radio that "seems not to work 100%"...

The truth is that since I have the navi (a TomTom Go Live 1000), I don't really need radio anymore, except maybe to listen to music - but then I have an iPod Touch with everything I like on it and with perfect quality (FM is not the best, regardless of Toyota's radio). Traffic problems show up directly in my Navi - so what do I need the radio for really? maybe in case of some huge disaster or something like that, in which case I hope I am not in the car or I can hear it with the not "100% working" FM radio Toyota does not want or cannot fix....

 

I will have to agree that it is a hopeless cause. I get phone calls, emails, surveys from Toyota how concerned they are about fixing the problem but its just a smoke screen. They know exactly what the problem is and have no plans to fix it, they just hope we will get tired of trying to get it fixed and it is working. Toyota has put in 2 radios and now they want to put in the 3rd, which I know it will not fix it. I am convinced that it is an interference problem from the car effecting the radio signal, especially since you put in a non-Toyota radio. Lets all keep in touch and if we ever find a fix keep us all posted.

 

You might want to read this - if this is not an isolated case, then maybe they are using a newly designed radio...

 

Hello,
I just joined, but have followed the FM issue with interest, as I have two 2010 Prius (V)'s. I just recently had both radios/navigation units replaced under warranty. I no longer have an FM audio problem with either weak signal or noise. I drive in areas where the output was previously poor, and now it sounds nice, like every other car I've owned. I'm very happy.

KJoh

 

It is a good news. Hopefully Toyota will spread this TSB to other models and to Europe as well.

 

I just got the TSB done yesterday on my JBL/Nav and FM still sucks vs my other cars. Back to the dealership then I guess. This is very frustrating as I do love the car otherwise.

 

I've a strong feeling that changing the radio can't impact on the fundamental issue of the high EM fields the car emits.

Interesting to note that the increased background EM noise from the Prius has been picked up by Wikipedia, here: Toyota Prius - Wikipedia, the free encyclopedia , albeit on the basis of (probably non-existent, in my view) health concerns. Still, at least it seems that someone else has measured EM field strength around the car and found it to be high. Given the criticism that has been levelled at the testing I did when I first raised this months ago, I find the Wikipedia entry somewhat vindicates my own work (and before someone asks, I didn't have anything to do with the Wiki entry, some of health stuff mentioned borders on quackery in my view).

Jeremy

 

I'm now running a Pioneer (Z120BT), and ran a random Chinese thing - each had great reception (relative to the base radio) in the Prius. I'm remote in Orange County, and both radios get better reception than our Lexus (GX470), and Nissan Xterra, Funny thing - I now can listen to 91.1 San Diego in many areas...

Having run 2 stock Toyota (non-JBL), 2 Chinese things (random 2Din models), and the Pioneer - over to Gen III cars, IMHO, I do not see a design issue with the US antenna (unless you don't connect the blue power wire).

As a 'fringe' person, my experience points directly at the radio.

 

I agree on the antenna and car generated noise, at least for my own Gen 3 model II with non-JBL system. I actually get good AM and FM reception here in the Sierra Nevada foothills. Lots of hills and canyons that make reception a problem and my radio is as good as any other car radio on weak stations, better than most I have tried.

I don't doubt that others are having problems and that problems are common, but they aren't universal.

 

I have complained to Toyota many many times, Written to them, have the radio switch out again and still the same, as soon as I get back to OH they are going to replace the radio again. I have said over and over again the problem is RF coming from the electric motor or somewhere in the engine area. Find a place where you can stop where the radio reception is poor, turn off the car and turn on accessories only I will bet the reception is great, now turn on the car again and static is back. I think Toyota knows what the problem is and have just decided to ignore the problem because of cost to repair or just don't want another recall. I know many Prius owners think this is a minor problem but I paid for a radio that was supposed to work. How long have radios been around, its not new technology.

 

I own a 3Gen base model. My radio reception is bullshit, the worst of all the radios i had ever.

In one or two weeks i'll try to change the oem radio and put an older radio i use in my older car. This older radio has better reception than the prius one.