[SOLVED] FM Radio Doesn’t Work But AM Does

Your stock car radio probably wasn’t the reason why you bought the car, but it’s definitely an added bonus. That’s why it’s not the best feeling when it stops working optimally. A common problem that car owners face is that the FM radio stops working but they can continue to use AM Radio. 

While it might seem strange that the same radio can work in some conditions and stop working in other conditions, there are a few reasons why this could happen. 

Why does my FM radio doesn’t work but AM does?
Here are a few reasons why your FM radio is not working, but AM radio is working: 

  • Antenna corrosion
  • CB radio interference
  • Broken cable

On that note, if you’re in the market for a CB radio: you should check out our article on the best CB radios in the market. 

Top 3 Reasons why your FM Radio Doesn’t Work But AM Does

FM Radio Doesn't Work But AM Does

It’s definitely a strange situation to be in when your FM Radio isn’t working but the AM radio is! No, your car isn’t forcing you to tune into those obscure AM radio channels! There are actually a few sensible explanations as to why this is happening to you. 

Reason #1: Antenna Corrosion

Car Radio Antenna

If you have a steel antenna on your car, the sad news is that it’s susceptible to the number one pesky problem all car owners face: corrosion. Yes, even your antenna can get corroded and this will definitely cause a problem with the radio channels playing clearly. 

The reason why it’s so difficult to diagnose this particular problem is that antennas don’t always look visibly corroded. What happens often is that your antenna looks perfectly fine from the outside, but it has a lot of corrosion and rust on the inside.

We know what you’re thinking: if the antenna is really corroded, then why is it able to play AM radio channels with no hiccups? Shouldn’t both FM and AM stop working?
Not exactly. 

AM radio signals can be picked up much easier and from further away. This means that even a little bit of rust or corrosion will directly impact the FM radio channels and stop them from working. 

In order to ensure that this is really the reason why you’re struggling with listening to FM Radio channels, you will have to take the antenna apart and have a good look inside it to locate the rust and corrosion. Sometimes, you won’t be able to witness any visible signs of corrosion, but you might see chipping away and general signs of wear and tear. 

Solution: You have two options with this particular issue. Either you can work on repairing the current antenna or focus your energy on replacing the antenna with a completely different one that won’t give you trouble.

It might not be that difficult to clean the antenna. You can wipe off the visible rust and corrosion with some WD40 spray which should really help in cleaning it. We recommend that you focus on cleaning the base of the antenna as well. You might need to open the hood in order to access this better. The WD40 spray will definitely help you get out any mild corrosion or rust and will also aid in removing any dirt, debris, or chipping off paint. You’ll be able to do a much better job at targeting the antenna cleaning than any car wash can. 

If you choose to place the antenna, consider replacing the entire radio system itself if you’re using a stock radio. However, if you don’t want to make that decision, you can simply switch to a rubber antenna. A rubber antenna is less attractive, but will never get corroded or rusted ever again. 

Reason #2: A CB Radio Interference

A common reason why FM Radio is malfunctioning is because of the presence of the CB Radio. Even if you don’t have a CB radio, it’s possible that your car was previously used for one (if you bought a second-hand car, that is). If you’re certain that your car never had a CB Radio connection, you can skip this point. 

CB Radio Interface

The reason why a CB Radio could cause issues is that some of them are equipped with adapters that connect directly to the factory radio antenna instead of having their own CB Radio antenna. You don’t have to worry much about this, except to try to remove the CB Radio first and see how it impacts the functioning of the FM Radio itself. 

Solution: You should unplug and dismantle the entire CB radio setup if we’re trying to eliminate this as the cause for the issue. Once you’ve done that, restart your car and check if the FM Radio is working properly or not. If the FM Radio magically kicks in and starts working: it’s easy to see that the CB Radio was at fault for somehow interfering with the radio signals.

If the FM radio doesn’t work, we know that it is probably corrosion and doesn’t have anything to do with the CB Radio itself. 

Reason #3: Broken Cable

There’s not much explanation needed as we’re sure you can picture how a broken cable can interfere with the functioning of the radio signals and get in the way of FM channels playing correctly. Before you try to get into the messy task of cleaning your antenna, take a good look at all the cables inside your radio system that connect it to the speakers and other components. Wires are always at risk of being slit, corroded or burnt, especially when they’re inside a car where they are constantly exposed to high extreme temperatures and sharp edges of other parts. 

The reason why a broken cable could be interfering with the FM Radio signals and not the AM radio signals is that the AM Radio signals are different and can be picked up much further away from the transmitter. Think of the AM Radio signals as much more resilient than the FM Radio signals. 

Solution: It’s a good idea to replace any of the broken cables that you’ve located as the culprit. However, try to figure out if it was simply worn and tear that caused the issue or if they were in contact with the sharp edges of another part. In the latter situation, you can easily insulate the new wires from meeting a similar fate.

Conclusion

We hope that you were able to easily locate the issue of why your FM Radio signals were not getting picked up and getting played. A good rule of thumb is to take the working AM signals with a pinch of salt since they are so resilient.
This is also a great opportunity to think about replacing your radio system. It may simply be more worth it to do a replacement rather than work on fixing the corrosion or other issues since no one can tell if these issues will crop up again in the future or not. Especially if you’re using a stock radio, you can truly benefit from purchasing a great aftermarket radio system in your car that is more premium and durable and won’t cause any of these issues in the future!

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