Why Is My Car Radio Not Working After Rain? 5 Tricks To Fix This


It often happens that while you are driving during the rain, you notice that your car radio is dead. You want to know what is wrong, fix the problem, and make sure it doesn’t happen again.

Though rain-related radio problems are often a canary in a coal mine, they alert you to unseen and unrecognized issues, as finding them now and fixing them could save you a lot of time, money, and repairs later.

As a general rule, to fix your car radio that stopped working after rain, check if your antenna’s wiring is wet and ensure the head unit’s wiring is free from water. Even if it starts working again, a car radio that malfunctions in the rain may indicate leaks, which can permanently damage the electrical system.

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In this article, I will go through common issues that cause car radios to quit working during and after a rainstorm and will explain the topics below:

  • How to repair your auto’s rear defogger grid without replacing the back window
  • How to determine if your antenna has a loose or corroded connection
  • How to protect a damaged shark fin antenna’s electronic innards
  • How to protect your ground wire connection from corrosion and moisture.
  • Where to mount your windshield antenna for best reception
  • How to dry out a wet head unit with silica gel

Check if Your Antenna’s Wires Are Getting Wet

Every radio signal starts with a transmitter broadcasting through a large antenna. Those radio waves travel until they reach a receiving antenna. 

The radio antenna captures the waves and concentrates them like a magnifying glass. This signal passes to your head unit, which amplifies the signal so your speakers can reproduce it.  

You will usually find your radio antenna in one of four locations: your rear defogger grid, your fender, your roof, or attached to an inside window of your car.

Check Your Rear Window Antenna

Unfortunately, if your car radio stops working in the rain when you’re using the defogger, it may be unavoidable. Defoggers work on the same principle as your toaster and electric space heater which means, an electrical current passes through a metal and resin grid. 

In many new vehicles, the rear grid also serves as your car’s radio antenna. When working as a defogger, the current generates resistance in the metal, which becomes warm. This helps evaporate fog and condensation to clear the window, yet the electrical current also creates interference in your radio. 

If you want to listen to your radio and use your defogger, you will need to upgrade your antenna.

Tip 1: Repair Your Broken Defogger Grid

If the problem persists after you turn off the defogger, you may have a broken defogger grid. Defogger grids are fragile and can break down with use. If you notice that one or more of your defogger strips no longer work, those connections may be broken. This not only interferes with your radio reception but also with your view in the rear mirror.

Replacing the rear window is an expensive fix to your problem. Repair kits like the Permatex Defogger Repair Kit may solve your defogger and antenna worries for a lot less money.  

When testing your defogger, it is good to use a test light. I am using and can recommend JASTIND LCD Circuit Tester, which is cheap and works great.

The video below from 1A Auto will show you how to repair the defogger grid on most car makes and models:

Check Your Fender-Mounted Antenna

Rear-mounted antennas offer better reception than rear window antennas, but they also have more failure points.

The wire between the fender and the car’s head unit runs across the entire length of your car’s body. Leaking water at any of those points could lead to interference and cut off the signal.

If your radio is working when dry, check your fender antenna with a “jiggle test.” Turn on some music, then walk out to the back of your car. Gently jiggle the base of the antenna while the music is playing. If reception fades in and out, your fender antenna is not firmly connected to your car’s body.

The chances are good that this loose connection has allowed water to seep between your antenna and its mount.

Tip 2: Clean or Replace Your Antenna

Remove the car antenna and check for rust or corrosion. If you find any marks of rust, you can clean it off with a Scotch-Brite Heavy Duty Scour Pad dipped in vinegar.

Or, you may find it easier to install a replacement antenna from your dealer or your auto parts store. While many automobile antennas use a “universal mount,” your make or model may use different fittings.

Check Your Roof-Mounted Antenna

Once upon a time, long metal antennas perched proudly atop your car. While these antennas offered superior radio reception, they were vulnerable to damage from vandals, underpasses, and low-hanging branches.  

Today, most roof antennas are considerably smaller and use tightly coiled copper to pick up signals. Shark Fin antennas are increasingly popular, as they can boost AM/FM radio, GPS, satellite radio, and cell phone signals! 

As it were, these antennas have less surface area than antennas of yore, ergo worse reception of incoming radio waves.

The antenna’s mount includes a tiny amplifier that boosts the signal before it reaches the head unit to compensate for its smaller size. And, like all electronics, these amplifiers are vulnerable to water damage.

If you are getting lousy reception (or no reception at all) after a rainstorm, your antenna’s seal may be breached. Shark fin antennas are far less prone to branch-related damage, but they are still delicate items that can be damaged with a blow. Even the impact of a small bump may lift your shark fin almost imperceptibly. 

You may not even notice any damage upon a casual inspection. However, if you can see even a tiny gap between your shark fin and your car roof, your shark fin’s delicate electronics are at risk of water seeping in and shoring them out.

Tip 3: Silicone Seal Your Sharkfin Antenna

You can alleviate any gap issue short-term by using Rectorseal High-Temp Silicone Seal. High-temperature silicone will withstand the heat of a hot roof in summer and keep out rain in winter. But in the long run, you will probably want to replace the shark fin altogether.

This video will show you how to install a replacement shark fin antenna:

Check Your Windshield Antenna

Windshield antennas, although not the most popular, are easy to install. Instead of drilling a hole in your fender or car body, you simply affix your new antenna to an inside window. One of the most common mounting areas is the center of the rear window.

But if your car came from the factory with a rear window defogger antenna, your windshield antenna’s performance may suffer. The interference which makes a heated defogger useless as an antenna can also affect your rear windshield antenna’s reception. 

Tip 4: Move Your Windshield Antenna

If your reception cuts out when you are using your defogger, try mounting the antenna on your front windshield.

The front defogger relies on hot air blown up from the engine, not electrical currents. That should allow you to enjoy music on a rainy day with transparent front and rear views.

Check if Your Car Radio Got Wet

Rain does terrible things to head units. The water is not the problem so much as the impurities it carries. Even after it dries, water can leave behind conductive materials. These can lead to equipment-wrecking short circuits, so do not overlook them. Even a tiny leak can cause big problems.  

If your car stereo has been exposed to moisture, Intel Electronics provides a way you may be able to save the stereo using silica gel packets for a “dry soak.”

Although many people may recommend rice, rice is less effective and may get inside your head unit and cause further issues.

Tip 5: Use a Silica Gel Dry Soak

Remove your damp head unit and do not turn it on. Exposure to water will damage electronic equipment over time. Running current through wet electronics can do immediate and possibly irreparable damage. 

Here are the steps:

  1. Gently shake the unit to get out as much water as you can.  
  2. Use a microfiber cloth to wipe any screens or lenses, then pat the unit’s exterior until it is dry. 
  3. Use compressed air to blow out any stray moisture, but make sure you hold the can straight up, so you don’t get more liquid into the unit.
  4. Use a hand vac to draw out moisture. Don’t get it too close as you don’t want static electricity or excess suction damaging the circuits.

When you complete these steps, put your head unit in a container and cover it with silica gel packets. Aquapapa Silica Gel Desiccant Packets should be enough to surround most damp head units, and this is the cheapest way to get rid of unwanted moisture from your electronics.

Cover the container to keep out moist outside air, then turn the head unit over every hour or two to ensure all water seeps out. Let it rest in the silica gel packets for at least 24 hours.  

The silica gel packets absorb moisture from the air. This lowers the container’s humidity by as much as 40%. As water evaporates into the dry air from your head unit, the silica gel sucks it up and traps it in tiny, interconnecting pores.  

A moist head unit should dry out within a day but keep it in a ventilated place. A thoroughly soaked head unit might take as long as a week to dry out completely. To speed the process, you can:  

  • Keep the head unit in a warm location, such as near a radiator–do not use a hairdryer or put it in the oven.
  • Ventilate it with a small fan.

After a day or so of drying in silica, place the head unit on paper towels or napkins. Wait four to six hours. If you see no signs of moisture on the paper, your head unit is now dry.  

The silica gel dry soak is not a guaranteed fix. The more moisture that enters your unit, the greater the chance it will be irreparable. Corrosive deposits may still plague your head unit and cause trouble later.

But if you want to hold onto your head unit until you can find a replacement, silica gel may buy you some time and, if you are lucky, may solve the problem altogether. 

Check for a Wet Grounding Wire

If your radio is not grounded correctly, you will get static and may get no signal at all. To check your head unit’s ground connection, you will have to remove it.

Taking out a car radio typically involves removing dash panels. Check your owner’s manual (which you can find at Car Manuals Online if you don’t have one in your glove compartment) for specific instructions.  

How to Ground Car Radio Properly?

When you have your stereo out, follow the ground wire to the point where it is bolted to the chassis or frame. If your ground wire is loose or you see corrosion or rust, tighten or clean the connection.  

You can also move the ground wire to a different area but avoid grounding to the same bolt or section as another electronic device to prevent humming from “ground loops.  

How to Ground Car Antenna Properly

Your antenna also has a ground wire. If that ground wire is corroded or if it gets wet, your signal will be degraded or lost altogether.

To check this, open the trunk or hood of your car. Rear-mounted antennas will typically be grounded in the trunk, while the ground for front-mounted antennas will be under the hood.

Pull the ground wire till it reaches a bolt on the car frame. For best results, connect the ground wire to a cross piece or hinge attachment rather than a bolt attaching the body to the frame.  

Remove the bolt with a socket wrench and clean it until it is free of any debris or rust. Then, coat the bolt and bare copper wire at the end of the ground with a dielectric grease like Super Lube High-Dielectric and Vacuum Grease

Dielectric grease protects against moisture and debris and increases conductivity. Finally, wrap the wire around the bolt and reinstall it tightly. 

For additional security, you can coat ground connections with a waterproof sealant like EELHOE Liquid Electrical Tape. After applying, wait at least four hours to allow it to dry.

The thick liquid becomes a vinyl polymer that will keep out moisture and prevent corrosion while ensuring your connection stays connected.

Seal Leaks to Protect Your Radio and Your Car

Water leaks can damage more than just your radio. They can also cause mold in your carpeting and upholstery and corrosion to the electronics that control your car.

With water in the car, everything from your power windows to your car’s electronic control units may be at risk. Small leaks can grow to significant leaks and cause even bigger problems.

Search the interior of your car for water stains or rust: these point to leaks. Water can pool inside your door panels where your speakers are located, and also sunroof seals often break down and leak. These leaks can send water trickling down the roof liner into your dashboard, wreaking havoc on all your electronic equipment.

If you hear wind noise when driving or notice water pooling in the passenger area, there is a good chance a door seal is failing. Inspect the doorframe and the door’s perimeter, as you may find holes, cracks, or rubber that has grown stiff and hard. You should be able to get replacement sunroof and door seals at your auto dealer or an auto parts store. 

If you have noticed moisture on your dash while driving through the rain, your windshield seal may be worn or cracked. A leaky windshield seal sends water directly down into the dashboard. Left untreated, this can be catastrophic, and not just to your head unit!

You can have the seal refitted by a repairman, or you can try filling in open areas with a sealant like Permatex Flowable Silicone Windshield and Glass Sealer.

Keep in mind that also car trunks frequently take on water. The rubber trunk seal can be damaged, or water can leak in through a tail light. Any water which finds its way to the trunk stays in the trunk at least until gravity sends it to the interior when you drive downhill.  

This rush of water is bad news for your rear speakers and trunk-mounted subwoofers, and since wires run throughout the length of your car, it is terrible news for your vehicle as well. Check your trunk seal and lights and replace any broken seals and caulk any gaps you find in that area.  

Conclusion

A silenced radio is a bad thing, but every cloud has a silver lining. The odds are good that if you’re having problems with your radio during or after the rain, you have a leak somewhere in your car that needs attention.

It’s better to miss out on your favorite podcast or get cut-off from the latest chart-topping song than endure the time, money, and repairs it may take to fix such an issue later.  

Source

Crutchfield: How to Choose a Replacement FM Antenna for Your Car

Instructables Workshop: Car Body Leak Repair

Intel Newsroom: What to Do When Your Electronic Device Gets Wet

It Still Runs: How to Get a Good Ground on a Car Antenna

Lifewire: Curing Car Audio Static

Popular Mechanics: How to Fix Your Car’s Weatherstripping

Martin

Welcome to ImproveCarAudio! I am Martin, and I love to write about everything related to car sound systems. I strive to provide the most accurate and helpful information about car audio through extensive research, as well as my experience with car audio installations.

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