FM radio discovery

I changed my running lights (the little bulb above the head light) to LED's now I have no reception with the lights on, strange

 

Ha. What you're experiencing has all the earmarks of low signal to noise at the radio input. Speaking as a EE, ham, and occasional EMI/EMC tester, what I think is wrong with your radio is a poor connection between the antenna and the radio.

The connection is probably broken or just not plugged in right. With a low level signal, with no noise present, you have just enough signal to get into the radio. A HID (High Intensity Discharge) light throws an arc; arcs are, electrically and radiatively, noisy. (Think about the pfft your hear on a radio or TV whenever a lightning bolt goes off nearby. Same effect, although the lightning bolt is a lot bigger.) Under normal situations the HID noise wouldn't be big enough to give a healthy radio signal any trouble - but, if you have a lousy connection, that additional noise may be the straw that broke the camel's back.

Basic moves: Get the cover off the radio, pull it out or feel behind, and verify, for sure, that the coax is plugged solidly all the way into the radio. If you give the thing a shove and all of a sudden your radio picks up all the weak stations in your area, you're good.

If it is plugged in, then unplug the thing, get out your favorite ohmmeter, and check continuity from the unscrewed antenna socket in the back of the car to the center pin on the coax. Anything over an ohm or so is bad news. Even more bad news is if the resistance reading varies wildly if the coax is twisted. Also, take a close look at the coax connector. They tend to be crimped on - but this wouldn't be the first time a bad connector gave people grief.

If the coax checks out OK, then my nickel is on a bad radio. This stuff happens. Speaking as a person who has rolled their own radio from dinky little parts from time to time, not to mention fixing radars at sea, there's ways to test the electronics to make sure they're working OK, but your dealer is not going to be one of the places where that kind of testing can happen. Get them to replace it under warranty - and, for sure, don't let yourself suffer with it. I've listened to my Prius radio; it sure doesn't seem to have a problem with weak stations that I've noticed, so I think you've got a real problem.

My bet: Had the radio been flat out dead, people would have noticed and you would have never seen it. It's working just well enough to have escaped the factory, but it appears that it hasn't escaped your notice!

Go give 'em heck, and good luck!

Kbeck

 

Ah your second post, welcome, nice to have another Electronics savy person out here.
You have discovered a minor offshoot thread to the Poor Reception in my 2010 FM Radio Thread.
We dismissed that point a while back. It turns out the front end unit of the FM receiver is as deaf as a bloody post. To bring you up to speed, dealers are now repacing the HU unit with some success. there are others who outright used a different receiver with the existing antenna pkg and report good results
I have also wondered if the built in antenna preamp is putting out to much signal, thus oveloading the front end. But I can't get my hands on somebodys car to hook a spectrum analyser up to the antenna cable to see just what kind of RF Levels we are actualy talking about here!
I have a 2008, it receives fine, but then I live in probably the 2nd most RF saturated city in US, and ironicaly hardy listen to Wide FM, I have 2meter/440 for NFM and a Uniden 996XT for Public Service and trunked calls and a Ipod to keep the ears busy.
I do love the Ipod, no extraneous talking, and all the songs just happen to be my favorites!!!

Anyway, again welcome, the more input, the better the discussion!!

 

Here Mate, read this thread. You are not alone!!!

http://priuschat.com/forums/gen-iii...07-weak-fm-radio-reception-in-2010-prius.html

 

HID's electronic balasts generate the higher harmonic waves probably, they are reflected by poor Prius FM tuner. I have no idea why simple LED bulb replace has a similar efect.