Weak FM radio reception in 2010 Prius?

AAAARGH !
Well, as it turned out the replacement radio made no difference.
After a second service appointment with the 'Master Tech' mechanic this time.
it was determined that there is rodent damage to the antenna cable and
that is why there is no reception. Spoke with Toyota Customer Service in
California and they echoed what the local dealer Service Manager told me:
Rodent Damage is not covered under warranty. About $700 to fix
I am NOT happy!
As mentioned to 'Toyota' - I have 3 cars parked in my driveway -
Never had an issue with Rodent (mouse) damage with other 2 nor with
the cars I had before the Prius - including a 1996 Honda with 238K miles.
Why did this happen to a car less then 6 months old!?
This is a big Quality issue. I see where I am not the first person to
experience Gen 3 Antenna cable damage and indeed saw another PC'er
note that engine wiring was damaged by mice. Is Toyota making their wiring
out of cheese?
Living in a rural area, I have seen where rodents and mice get in to
engine compartments and leave acorns and etc - but have never experienced
any functional impact to any vehicle I have owned in over 30 years of
car ownership.
Fortunately, the AUX input and disk player still works on the unit
and overall, except for this event, I am pleased with the vehicle.
However I am now concerned about the future viability of this vehicle.
Not sure if I should move/copy this post to a more appropriate forum
for follow-up advice in dealing with Toyota. Suggestions welcomed.

Back on topic, sort of, FWIW - the loaner car the dealer lent me - a 2011
RAV-4, also had weak FM reception just like the Prius.
Both far weaker then the factory unit in our 2009 Kia Rio!

 

I wish someone would clearly document the spot(s) where they get in, so we could wire mesh that area...

 

Where they found the rodent damage, close to the HU or some other place? BTW. you can fix it yourself by replacing the damaged piece of cable. It is a magic, it is just a coax cable linked together with a power wire for antenna amplifier. 700 bucks looks to be quite expensive fix.

 

Damage is behind Passenger side window pillar. "Vehicle will need two harnesses in the Right side A-pillar"
Yes - the repair cost quoted is VERY expensive.

Agree! - Would also be even nicer if Toyota owned up to, and fixed this serious product quality issue.

 

Strange! We have a 2007 RAV and 2010 Prius and FM reception is very good. It is not that fast in changing to alternative frequency for the same station but this does only a dual tuner radio like Kenwood has. We have absoultely no issues with our European cars. I had some with the 08'Caddilac CTS4 where the quality was not good.

 

I believe the radios you get in Europe are completely different radios than we get in North America and are made by a different company.

 

Absolutely not true in this part of Europe, I'm afraid!

I have now fitted three replacement radios to my EU Prius, in an attempt to overcome the appalling FM radio performance, especially when the signal levels are a little low (as they are where I live). I've put the car in an RF anechoic chamber and found that it has unusually high levels of RF noise when powered up.

If you live in an area with strong FM transmissions then the radio performs adequately well, but go anywhere where the signal level is a little weak and the radio performs very badly indeed.

I think that you're lucky, as my experience of driving in Switzerland is that it has placed FM transmitters in some very good locations and consequently has generally high FM signal levels over much of the country. Here in central Southern England we suffer from very distantly spaced FM transmitters that aren't installed on high ground, with the result that we have a lot of multipath and generally fluctuating signal strength problems. The vast majority of car radios sope with this well, the Prius doesn't, as the high background RF noise from the car systems interferes with similar strength wanted signals and creates a lot of additional noise.

Jeremy

 

I'm not sure about US, but AFAIK the major Prius's audio supplier is FUJITSU TEN. Some models use PANASONIC components and JBL external amplifier.
Based on about 2 year long discussion here, no one find the 100% reliable FM replacement, so Jeremy's findings are more or less accurate. The problem are not FM units theirself, but mostly Prius high voltage invertors and MG1/MG2 control. It is very hard to properly shield this type of equipment in automotive world without real ground connection. If somebody is tracking the GM Volt - are there similar findings?

 

Hmm, it is a very narrow space and quite hard to get in. Was there any trace of rodents?
BTW - If I'm a rodent, I'd find more easy accessible place to eat cable insulation.

 

No trace of rodents in the passenger compartment itself. Evidence - food waste
and droppings- in engine area. Have had evidence of a rodent presence in engine areas (Air filter, especially) in other vehicles - but NEVER any functional damage in any of my vehicles until this Prius.

 

The non-JBL radios that I am aware of in the US are Matsushita
(Panasonic). The one in my car is a 86120-4790 inf CQ-JS0960AJ and works well compared to other factory automotive FM radios in my difficult reception area. Since there is no such thing as 100% reliable FM reception in my area on any car radio I agree with your statement. However, my Priuss radio was pretty good on weak signal stations compared to other radios.

AM reception, OTOH, does suffer from car electronics noise on weak signals. It's not a complete disaster, my favorite AM talk radio station is 50kW and comes in listenable during the day near my home. I am 100 miles from the transmitter and not on one of the strong lobes in the stations antenna radiation pattern. If I go 10 more miles and one more small range of hills, it isn't listenable in my Prius but is in most other cars.

 

I tried an experiment to improve FM reception today. I purchased an in-line filter, intended to reduce amateur radio interference with FM radio. It needed adapting to fit in the aerial cable, but I found this was fairly easy to do by breaking the unit open and soldering the cable to the unit directly.

The filter is a high pass filter that blocks pretty much everything below about 80MHz. This means that AM radio no longer works, but as a lot of the interference from the car systems is below 80MHz I was hoping that the filter would also reduce the level of these signals getting in to the radio.

I haven't done a complete test yet, but the rough and ready testing I did this afternoon, just driving around the block, showed a very big improvement in FM noise. This has pretty much convinced me that much of the problem is noise from the car, as I've believed all along.

The down side of this mod is that you lose AM radio, not a problem for me, but it may well not suit everyone. The filter I used was one sold by the Radio Society of Great Britain as their HPF model for Band 2 FM radio, here: Radio Society of Great Britain EMC Filters I have no doubt that these are available elsewhere, too.

Jeremy

 

Jeremy, please keep us posted. If that is a universal Prius FM fix, it could always be installed with a switch so it could be bypassed for AM reception.

 

OK, here's another test update. I drove out to the area where I did the first experiment (detailed way back in this thread), to look a bit more closely at the interference problem. This area has poor FM reception and is roughly at the same distance from three FM transmitters, so tends to confuse the AF function on RDS a fair bit.

Last time I checked at this location, I found that there was a very marked increase in background noise on the radio when the car was switched from "accessory mode" to "ready mode". In accessory mode the radio reception was acceptable, in ready mode the background noise became intrusive, a fairly positive indication that the car emits a fair bit of RF noise when the inverters, power electronics etc are running.

This time the test results were completely different. In exactly the same location, with the filter fitted in the aerial line, there was no perceptible change in reception when switching from accessory mode to ready mode.

I still need to really see how this filter affects reception when driving in different areas, so can't at this time make a wholehearted recomendation, but I can say that the initial results look very promising. The downside, as mentioned previously, is that it prevents AM reception. It may be possible to switch the filter out with an RF relay, but this would add complexity and cost to the mod.

I'll update this in a week or so, once I've had a chance to do some testing in a broader range of conditions.

Jeremy

 

For those of us in the Colonies, UK FM Band 2 = 88-108MHz which is what is normally just called FM in the US

The radio should be rejecting the noise below 80 mHz without an add on filter, but that would probably add a dollar to the cost of manufacturing the radio.

 

You're spot on. I think the main issue (apart from the high RF noise level from the car itself) may well be that the radio has a very broad band front end, and this exacerbates the problem by allowing the higher amplitude interfering frequencies to generate cross mod/inter mod products in the radio which then creates the problem.

Jeremy

 

I think that someone who knows quite a bit more than I do about filters could design a relatively simple filter that blocked from just above the AM (MW) band to just below the FM band. Or better yet, a dual bandpass filter that just passed broadcast AM (MW) and FM.

 

I drove to another known bad reception area this morning and was very pleasantly surprised by the performance of the radio. The background noise level didn't seem to increase significantly right up to the point where the radio lost the signal (inevitable in the bottom of the valley I drove through). The radio re-acquired the signal much quicker than it used to, again with minimal background noise.

For me, at least, this mod proves conclusively that the problem with FM reception is exacerbated by high out-of-band RF signal levels getting to the radio front end and causing interference. I strongly suspect that these out-of-band signals are from the car high power electrical system.

The obvious fix for Toyota would be to do as you suggest, xs650, and fit band pass filtering in the antenna amp, so that only the AM and FM bands get through to the radio. I took the high pass filter I bought apart to fit it directly in-line with the cable and it was very simple, just three components, two capacitors and an inductor arranged as a pi filter. Total cost of the components would have been pennies. The capacitors were 12pF ceramic ones and the inductor was a dozen turns of insulated silver plated wire of around 20g wound to about a 5mm diameter with an air core. These parts were fitted on a very simple circuit board with the antenna cable soldered to each end.

I'm personally over the moon with this mod, as for the first time since I bought the car just over a year ago I have pretty good FM reception in my local area. Driving to the shops this morning was just great, as I could hear the radio pretty clearly for the whole way there and back, something I've not been able to do for a long time.

Jeremy

 

There is a picture of the filter on the RSGB web page I gave earlier, but as this was an experiment I didn't take photos of the mods I made to it to get it to fit, I'm afraid. I guess it could be adapted to be plug-in, by changing the UHF coax connectors it comes with for those used on car radios.

The filter itself is very simple, so I've drawn and posted the filter circuit diagram below. Someone might be up for making a custom version that will be plug-and-play for the Prius antenna. I've worked out the component values with the assumption that the filter has an 80MHz cut off and a 75ohm characteristic impedance.

Jeremy