Key Takeaways

  • A dead car battery would most likely be the issue for a no start/radio run issue.
  • A bad starter, ignition switch issues, or fuel pump issues could be the cause.
  • Use a multimeter to diagnose a bad battery.
  • Use brake cleaner to diagnose a bad fuel pump.
  • Use a hammer to diagnose a bad starter.

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When our cars won't start, we can feel like sitting ducks. But why would the radio work but the car not start?

A dead battery would most likely be the issue. You could also have a bad starter, ignition switch issues, fuel pump issues, electrical issues, or engine issues. But statistically speaking, the most common cause of this issue would be a dead battery.

I’m a mechanic with 5 years worth of experience diagnosing and repairing vehicles. I am ASE certified and received my degree in automotive repair. I receive training on the latest automotive technology. And I diagnose and repair vehicles with the latest automotive tools and software.

Table of Contents

Reasons Why Car’s Radio Might Work But It Won’t Start

When your car won’t start it can be frustrating. You may look for other symptoms and one of them might be a working radio. So why would your car not be starting but your radio working? Let's look at a list of reasons.

Car Battery

The most probable reason your car won't start is that you have a dead car battery. Your radio doesn't need much voltage to run, but your starter needs a lot. So your radio can function while the starter can be dead in the water.

Just because your radio is working doesn't mean the starter can. The starter motor needs about 12.6 volts delivered to it while the radio needs just a fraction of that.

In fact, electrical components in your car need much less voltage than 12 v to operate.

So if your car’s battery is ‘dead’, your car radio could still potentially work. Because a car battery doesn’t need 12 volts to operate. But your starter does. The starter will not turn over if the battery is below 12 volts. The radio and lights work in this case, but the car will not turn over.

When this happens, you may hear a bunch of clicking coming from the engine compartment. This is your starter relay clicking. When you hear this, you can be sure you have a dead battery and it’s time to replace it.

You might get lucky and it might just be the battery cables. Check them and check the battery terminals as well. If they are all in working order, it may be time to change the battery.

Starter Motor Issues

When your electronics work, but your car won’t start, you might have a bad starter. Your car battery powers a starter motor to get the engine going. If the battery is in good working order, but the starter motor is broken, you will experience a no start issue.

A car starter is powered by electromagnets. Sometimes, the electromagnets can start to fade away causing the starter motor to not work. In this case, your car headlights and radio would continue to work, but your car would not turn over.

The radio doesn’t rely on the starter motor to function, the radio just requires the battery to run. So your car starter motor being broken will cause the issue of your radio working but your car not starting.

Car’s Ignition System

Your car’s ignition system is responsible for supplying spark to the spark plugs. The ignition system is basically the engine’s electrical system. The spark plugs in turn ignite the air fuel mixture in the combustion chamber providing momentum to push the cylinder down and turn the crankshaft.

If your ignition system is faulty, your car will not start. For example, if you don’t have a good ignition switch, power will never flow properly through the vehicle and your car won’t start.

The ignition switch is what powers the vehicle on and off. If there is no on/off switch, there is no power going to the ignition. This can be a major issue, and one that causes the radio to work but the car not to start.

If you have a faulty ignition switch, all the electrical components of the vehicle may work but the vehicle may not start. A faulty ignition system will cause your car not to start but will leave the radio working.

Faulty Fuel Pump

A faulty fuel pump can cause a car not to start since fuel from the gas tank isn’t being delivered to the engine. This usually sounds like the car wants to start, but instead of starting, it just continues to crank over and over.

No starting ever happens because the engine is lacking fuel. The radio will start because all the electronics in the vehicle are in good working order.

The fuel gauge may or may not be working with a faulty fuel pump. So if you just filled up and the gauge says empty, look towards a bad fuel pump. There are ways to test a bad fuel pump which we will go over later in this article.

Engine Issues

Sometimes, your engine might not be up to par. This could mean that it just doesn’t want to start for a variety of reasons. Some reasons might be that the engine is hydro locked, or it’s overheated. A damaged piston could be the issue or a broken timing belt could cause a car not to start.

In these cases, the radio might continue to work because it’s still drawing power from the battery, yet the car will not start because of other issues. So if your car isn’t starting, and you checked all the issues above, it may be time to take your car to a professional to get it properly diagnosed.

These are the main reasons why your car radio might be working but your engine is not turning over. Check all these items if you can. They are pretty simple to check with the right tools and equipment. And the equipment is pretty affordable to purchase.

But if you are in doubt, take your vehicle to a mechanic who will be able to diagnose the issues in no time. No start issues are some of the most common types of repair jobs a mechanic sees, so they diagnose them all the time.

They will probably be able to tell without even looking at the car. When in doubt, take it to a mechanic.

Checking For A Faulty Fuel Pump

If your car refuses to start, and you suspect a fuel pump issue, you can check it by following these steps. If your car won’t start and you're unsure if it’s the fuel pump, grab a can of brake cleaner and follow along.

First, remove the air intake box that’s usually attached to the air filter box. This will expose the throttle body. This is where you're going to spray the brake clean in.

Next, with the air intake box removed, have someone turn the ignition switch on and start cranking the car. This will mimic starting conditions. And as someone is cranking the car, start spraying brake cleaner into the air box.

Make sure to do all these steps with the vehicle in park, and with extreme care. As you spray the brake clean into the air box, the engine will think the brake clean is fuel and suck it into the engine on the intake strokes. It will then compress the brake clean and combust it.

If the engine starts as you are spraying brake cleaner into the air box, you can be sure you have a fuel delivery issue. The fuel pump is failing to deliver fuel to your engine from the gas tank. But the fuel you're adding up top is working.

So by process of elimination, you have narrowed down the fact that your fuel pump is the issue. If you spray brake cleaner into your intake and the car still doesn’t start, you’re going to have to start looking elsewhere for your issue.

The brake clean trick only works to diagnose a faulty fuel pump.

Diagnosing A Car Battery

Diagnosing a bad car battery is really straightforward as well, but you need a multimeter. A multi meter is a tool that measures electrical current. You can pick one for $10 dollars on Amazon and they are good tools to have around.

Hook up the leads to the terminals of the battery. You should have a reading of 12.6 to 12.8 volts. This means your battery has enough voltage to supply amperage to the starter. This means your battery is good on voltage. This doesn’t mean your vehicle’s battery is good though.

To finish the test, you need to keep the voltmeter attached as you start the car. Watch the voltmeter’s reading as you start the car. It shouldn’t drop below 10 volts. If the battery drops below 10 volts, you have a bad battery.

If the car still doesn’t start, but the voltages remain in spec as you start it (above 10 volts), you have an issue other than your car battery. If your voltage drops below 10 volts and doesn’t start, remove the battery and replace it.

Replacing the battery should fix your issues.

Hammer Trick For Starter

If your starter is the cause, sometimes smacking it with a hammer can fix it. The starter is a rotational magnet. And the magnet can get caught in a dead spot. So when you hit it with a hammer, it rotates the starter off the dead spot and allows it to start again.

It sounds archaic, but it’s a trick all mechanics use to test whether a starter motor is bad or not. Here’s how you do it. The first thing you need to do is locate the starter motor. It’s usually located somewhere between the transmission and engine.

It’s on the flywheel, and the flywheel connects the transmission and the engine. Now if the starter motor is exposed enough, just smack it with a hammer at 50% of your effort. Do this around 8-10 times. This will be enough to fix the starter.

If the starter is buried, take a party bar and touch it to the starter. Then hammer the end of the pry bar. This is the usual method of mechanics since modern cars have their starters buried so deep. If you hammer the starter, and then it eventually starts, you have a bad starter.

It’s time to replace the starter.

Reasons Why Your Car's Radio Might Work But It Won't Start

About The Author

Christopher Sparks

Christopher Sparks

Christopher Sparks has been servicing vehicles since 2012. After completing the automotive studies program at Camden County College, he was awarded an Associates's Degree in Applied Science. His first job was a lube-tech at Jiffy Lube, and is currently an independent B-Technician servicing vehicles for the United States Postal Service. Christopher is ASE certified and loves rebuilding engines.

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