FM tuner "broken" '94 Sundance

I drive a '94 Plymouth Sundance with a factory installed AM/FM Cassette radio. The AM works okay and the cassette as well could probably use a clean. However the FM does not, neither hand tuning or the seek function will find a station, the seek function just keeps zipping around and around the dial. Am prepared to buy a new one but before going that route is there anything I can do to get the FM back?

Thank you.

Are you sure the antenna is properly connected? If the tuner can’t pick up a station it won’t lock in.

Aftermarket radios with cassette players are getting hard to find.

Since the AM section is working that pretty much indictes the antenna should be ok. It is harder to receive AM signals without a good antenna connection than it is FM signals due to the wavelenghts. The trouble is most likely due to a failure inside the radio and repair is needed to fix the trouble. Economically speaking you would be better off purchasing a new radio rather than repair the one you have. If you wanted to get the same model unit you might be able to find a replacement on Ebay for a good price.

The AM uses an internal antenna so check you external antenna hookup at the radio AND the path it takes to the outside looking for rub through wear that would ground it out.
If all is well you have radio problems internally.
Take the radio out and give the circuit boards a good cleaning. Electrical circuit cleaner aerosol can be obtained at Radio Shack and others )
Still doesn’t work ? Time for a new radio.

Check the antenna from end to end, especially where it plugs into the radio…If your car has a “hidden” antenna (in the windshield) that connection is suspect. Ken G. is right about AM not needing an external antenna. FM does…Car radios are a dime a dozen…Don’t spend to much time messing with it…

I thought that the metal body of the car provided shielding so that an external antenna is necessary even for AM reception. The cars I owned in the 1940’s through the 1960’s which only had AM radios had antennas. When I was growing up, I tried to use an AM portable radio in a car that didn’t have a radio and it wouldn’t receive anything but a very strong signal. My first car, a 1947 Pontiac that I bought for $75 had a non-working AM radio. The antenna was broken. A new antenna fixed the radio. I think that the AM section does need an outside radio antenna. I would guess that a transistor is defective on the FM tuner side of the radio. The signal isn’t amplified enough so that the rest of the FM tuner stage can lock onto the signal.

If this is the only problem in the OP’s 1994 Plymouth Sundance, he is a very lucky owner.

Check the antenna as others have said. I think these have the ‘square’ radio that Chrysler used in cars for many years without changing the form factor. That means that if it’s not a simple antenna problem, that there’s dozens of these on ebay waiting for you, and they will likely just plug in. You can upgrade to a CD player in nothing flat by purchasing one of these. Or if you want something better, has some nice upgrades and will include a free wiring harness if you order from them.

As a side note, make sure your radio is set to “DX” and not “Local” if it has this feature.

Well this is an interesting discussion with different views on if an external antenna is needed to receive AM signals in the car. And with some good knowledgeable members here too. Frankly, I have to throw my hat in Triedaqs ring. Without an external antenna connection the AM reception will be dead. There may be an inductor coil in the circuit inside the radio to make the antenna connection electrically longer but I think an external antenna is still needed. Portable transistor radios usually use an internal ferrite rod for the antenna and oscillator circuits. I don’t think the portable AM radio will work too well in a car though due to the surrounding metal and the long wavelength of the AM signal. FM has no problem getting through the windows though with it’s much shorter wavelength.

Triedaq- Can I get a amen on that?

In the interest of science and technology I did a little checking on AM reception inside my minivan using my portable pocket sized radio. There wasn’t a great deal of attenuation on the signal using the radio inside the van but there was some. It didn’t like getting real close to the roof though.

Most small, inexpensive radios use a ferrite coil inside the radio to provide an antenna for AM reception…AM radio stations use transmitters operating at 50,000 to 100,000 watts so people in the third sub-basement parking garage can pick up the signal on a $5 radio…These powerful signals easily penetrate a car body…But since the external antenna is in place, it is probably used in the radios AM antenna system…The frequencies used for AM and FM are a long ways apart, so different RF tuning sections are needed for each “band”…

Today, if you are going to need enough of them, the entire device can be designed and engineered onto a single chip…The days of circuit boards filled with discreet parts are over. Anything that requires belts, pulleys, motors, spinning disks is history…A USB thumb drive can hold a thousand songs or a full-length movie…No moving parts. Radio and television broadcasters are having trouble making ends meet. Not enough listeners for commercial broadcasts anymore…The airwaves are being taken over by political and religious nut-cases who are funded by other sources with an axe to grind…

Caddyman, I think you will have to go south of the border in order to find a 100kw AM station.

Car radios are not the ones with the internal AM antenna it is portable radios that have this. Car radios need an external antenna to pick up AM. One of the big tip offs that you have messed up when you replaced someones radio is they say “FM is fine but no AM”. When Malibus came back in 1997 they had a antenna connector by the passengers foot and it was always getting disconnected. GM paid me .5 to hook probably a hundred of these back up over the years.

50KW spewing the mindless garbage that is the wasteland of AM these days. Not a good use of power IMHO.

Perhaps a good test would be to simply unplug the antenna from the radio, then see if it makes any difference to AM reception. If it does, the FM section is shot. If not, the antenna is probably at fault.

Somehow I doubt you’d get very good reception on your portable AM radio if you enclosed it in a steel case (like a car radio), then buried it halfway in the dashboard.

Also, to those that mentioned putting everything on a chip. Yes and No. You can put most of the electronics on a chip, but you still need the correct size inductors and capacitors for the frequencies you’re dealing with, and in the case of AM, that means you can’t miniaturize everything–some components still have to be outside the chip. With cell phones and the like you can get away with putting more RF components on the chip as the frequency is much, much higher.

A big AMEN to Cougar. I think if a person disconnects the radio antenna on an automobile radio, the AM signal will be gone. I remember having a tube type RCA portable radio that we tried to use in a car we had without a radio. The radio had a loop antenna built into the back cover. It wouldn’t pick up anything but a local station. Later, I had a Zenith portable “TransOceanic” radio. It had a wave magnet–a loop antenna that one could suction cup to a window in an automobile or a train. I never tried it, but I had seen one in use in the 1950’s by a passenger in a train.

I also agree with your comments Oldschool and Oblivion.

A big thank you to all of you, I’ll go the antenna route first and let you know.

You can remove the radio and disconnect the antenna lead followed by baring the end of a scrap piece of electrical wire (2-3 feet long) and inserting the bare wire into the small hole in the center of the antenna plug on the radio.

This will work as an acceptable test method to determine if the radio is at fault. If the reception is still crummy then you need a new radio.

This has been an interesting and informative discussion. But in this case AM works cassette works, FM doesn’t. Go to Wal-Mart get a cheap AM/FM cassette probably about $50 and call it a day. If you spend more than about $50 repairing the old radio you will likely exceed the value of the radio and in this case maybe even the car itself.

Try these folks: fixed my Dodge radio fairly cheaply…