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AM radio static noise while driving

When driving my 2005 Prius with the radio turned on to any AM station, I cannot listen to any AM broadcasts, as they are filled with static, hissing and whirring noise. The static becomes worse as I accelerate or brake, and stops when I stop at a red light or Stop sign. There is no such problem with FM stations. What is causing this? Is it my spark plugs?

Found this on a blog:

...there was a Toyota Service Bulletin on this specific problem, instructing them to disconnect the power to the radio, and re-connect it. They did that and the problem went away. That was 8 months ago. The problem re-appeared last month, and when I took it in, they again dis-connected and re-connected the power to the radio, and the problem again cleared up.

The issue supposedly is that shielding grounds are getting loose. Hybrids have lots of sources of static. Accelerating and braking especially bring the electrics into play.

Keep in mind that the AM radios of the last 20 years have been getting worse…not better. I think AM stations are also getting scarce and don’t transmit as strong as they used to. I used to work at a local AM station many years ago and it had a strong signal. Now…it’s a weakling. There is a local “call-in” AM channel that keeps asking it’s listeners to tell them how strong the signal is in the local listening area. They adjust the signal according to the replies. Sometimes the caller is weak and the announcer is strong or vice versa. By the time the first 30 minutes is up…they have the signal balanced. @insightful is right on the money. Hybrids have more sources of static than any other vehicle short of a diesel locomotive.

AM stations are disappearing from the airways and those that remain are often weak with hit-n-miss performance. Long periods of “dead air” is common when the local duplicator station has no commercial to fill in the minutes allotted by the programs source. FCC regulations have been drastically eliminated or ignored in recent years and AM especially suffers. And the current audio systems from the auto industry includes an antenna that might give excellant reception of Sirius-XM and FM but is quite poor receiving AM. Could there be a conspiracy to pressure the public to subscribe to a “pay for play” broadcast source?

I remember years ago when late at night many AM stations would suspend broadcasting. At that point the airwaves were less crowded and you could tune in to odd stations that were 500 miles away.

The FCC has, through the years forced many stations to cut their transmission power, and there are many more stations broadcasting now so the crowded airwaves result in an overlapping of the signals too.


The FM band is very crowded, @Yosemite. And the AM band stations would drastically cut their power at sundown because their signals would carry much further due to ‘skip’ at night. There were several clear channel stations that kept their power up and their signal could cover half the country. The Del Rio station that was actually in Mexico played C&W to truckers from coast to coast back in the good ole days.

“Could there be a conspiracy to pressure the public to subscribe to a “pay for play” broadcast source?”

I doubt it. AM doesn’t provide the clear, static free listening experience that either FM or satellite radio does. AM seems to be relegated to talk radio and sports, mostly, for that reason. It has been losing listeners for many decades. This isn’t a new thing. The only new thing on AM radio around here is Spanish language broadcasts. There has been a small Cuban community in DC since the 1960s, but the Hispanic community has been expanding all over the DC/Baltimore metro area in the last 10 years. The only bandwidth available for them is on AM.

There are people all over the world complaining about am and fm reception on the prius. Apparently the added another antenna in the side window in later models.

“I remember years ago when late at night many AM stations would suspend broadcasting. At that point the airwaves were less crowded and you could tune in to odd stations that were 500 miles away.”

Actually, some of them would carry for more than 500 miles.
Back in the '60s, when I was in high school and in college, the AM airwaves in the NYC metro area were devoid of anything other than various “Hallelujah Hour” broadcasts on Sunday nights.

One Sunday night, as I frantically twisted the tuning dial of my little Zenith transistor radio, I picked up WOWO, in Ft. Wayne, Indiana, and it was my…Sunday night salvation…for several years.

In addition to being able to hear the Top 40 Rock Hits that were unavailable in the NY metro area on Sunday nights, WOWO had ads for a hamburger chain that was unknown at that time in The East. The DJs on WOWO made the food and the shakes at…McDonald’s…sound like The Food of The Gods.

As I drifted off to sleep, I would listen to the music and the ads on WOWO every Sunday night, and I tried to visualize that…wonderful…hamburger joint on “The California Road” named…McDonald’s.

Yes, they can sometimes trump reality.

I did the same thing @VDCdriver; but it was a station somewhere down in Mississippi, and it would come in pretty clear up in southern Wisconsin. They played the top hits of the 60s and a few oldies from the 50s.
I had a room about 12 X 20 in the basement that was part storage and part for my Model railroad, wood model airplanes, and plastic model cars. I’d sit there building those models and listen to the radio on weekend nights when I was allowed to stay up as late as I wanted. Every penny I made mowing lawns, raking leaves, cleaning gutters and any other yard work got spent on models, paint, glue and anything else I needed.

I think I built 50% of every model car on the road at that time and every WWII fighter or bomber that flew in the war. I had a few wood sailing ship models , but never had the patience to keep at them. They can take a year or more to build.

I wish I had the room to do that again.
My grandsons nine and I’m hoping to get him interested this winter in the hobby.


rschlegel In the old days when AM was the only show in town most cars had to have distributer shielding to almost eliminate the static. I don’t think that would be a problem with the Prius. I agree with most of the posters that AM stations are now very local and weak. Around 1965 I could receive Wolf Man Jack at 100,000 watts from Tijuana Mexico a bit over 1,000 miles away on my 2 transistor hand held radio. Is there a particular AM station you prefer?

I remember WOWO very well and listened to the channel every weekend. Thanks for bringing back fond memories @VDCdriver and I always listened to the songs and commercials via the car radio. I had my first Big Mac and fries in 1973 just after I arrived at my USAF training base. We had to travel to Champaign, IL to get them but it was worth the drive.

"I had my first Big Mac and fries in 1973"

I don’t think that the McD’s chain got to my area of NJ until…perhaps…the late '70s.
The first fast food chain in my area was Gino’s, home of The Gino Giant.
That chain was owned by former football great Gino Marchetti.

Once McDonald’s & Burger King invaded NJ, Gino’s was no more.