Fixing A Car Stereo That Won’t Turn on But Has Power

How to Fix Car Stereo Won't Turn on But It Has Power

You’ve probably faced this problem tons of times. You’re on the road, and you’re trying to play some music while you’re on the go, but your car stereo doesn’t seem to turn on, even though it has power. When this happens, nothing seems to work.

Then suddenly, the problem goes away on its own after spoiling the mood, only to come back later. Pretty annoying, isn’t it? Not only that it’s frustrating, but this also could mean that you’re in for a huge repair bill. It might even extend to replacing the entire unit altogether.

Well, let me tell you the probable reasons behind this happening, and possible solutions to it.


Why Does It Happen? The Common Car Radio Problems

Although it’s quite possible that your entire stereo unit has failed altogether. Hopefully, there might be other possible reasons behind the radio not turning on.

Yes, even when it’s connected to its power source.

It could be a faulty or damaged wiring, a fuse that might have blown up, or even some anti-theft feature that might have gotten triggered when the battery died. Thankfully, most of these problems are fixable without having to replace the entire head unit.

The Protect Mode Problem

Common Reasons Why Car Stereo Won't Turn on - Protect Mode Problem

This is more of a technical issue rather than a hardware problem.

Several car sound systems come with an anti-theft protection mode that often tends to get triggered when the connection to the power source has been disrupted.

If the car was stolen, the thief will not be able to enjoy music from the car’s sound system. But the technology works both ways. The sound system will stop working if the power supply is disrupted.

If your car stereo has the anti-theft protect mode on, and you try to turn it on when there is a loss of power, you should see a display that is different from the usual one.

It’d either show you a screen that’d ask you to enter a code to get it started back again, or not operate at all. To troubleshoot this, you’d have to enter the code that it asks for (try looking into the user’s manual provided with the stereo), and follow the troubleshooting steps.

But if the display does not turn on at all, or goes completely blank after turning on, then it might be a different issue. If it goes blank and it does not have an anti-theft mechanism, you might need to take it to a technician.


Wiring Issues

Common Reasons Why Car Stereo Won't Turn on - Wiring Issues

A bad or faulty wiring could also be the reason behind your car stereo not turning on. This often happens while installing a new car stereo. If that is the case, then the first thing you’d have to do is remove the newly installed stereo and take a good look at it to detect what the problem actually is.

Next what you need to do is check the ground wire (black,) the constant 12V wire (yellow), and the accessory 12V wire (red) using a voltage meter. You can use a test light as well.

Now the question is, how’d you know if there’s something wrong with the wiring?

It’s pretty easy to tell. See, the yellow wire should always have power of 12V even when the car is turned off. The red wire is supposed to have 12V as well but only when the car is powered up. To test the ground wire, use another metal ground to see if it’s working properly.


Power At the Head Unit

If you’ve checked all the connections and the wirings, and you still can’t find the problem, then you might also take a look at the power at the head unit itself.

Car radios typically have two power wires; one that provides power to memory which always remains hot, and one that only heats up when the ignition key is activated. The radio’s power supply depends on these power wires, so it fails to work properly or not work at all if these are reversed.

When you see no power at the head unit, but there is power at the block, then the issue might be a broken wire. In that case, trace the power wire all the way back to its source and see where it’s broken. There might even be an in-line fuse hidden in there somewhere that skipped your notice before.


A Blown-Up Fuse

Common Reasons Why Car Stereo Won't Turn on - Blown Car Fuse

This is a common problem in a lot of electrical equipment. Fuses are incorporated inside electrical connections. These things are designed to blow up in case there is a power surge to protect the rest of the connection from burning out or catching fire.

Thankfully and annoyingly, they do their job well. In fact, they do it so well that they tend to blow up at the slightest hint of a rise in voltage.

There could be a handful of reasons behind this happening. It could either be caused by a battery replacement gone wrong. In this case, switch the faulty part with a new one.

There might be lighter socket that went bad. Trust me, you’ll have to spend some hours repairing it.

Whatever the reason, the only possible precaution to prevent this from happening is to monitor the voltage. In regular intervals. To do this, you’ll need a little equipment called a multimeter. You’ll find it at your local hardware store. In case you don’t find one, you can also use a tester as a substitute.

When it comes to replacing fuses, be careful not to replace fuse with a higher amperage one. Also, have your car checked thoroughly by an expert for underlying problems. A blown up fuse is usually the sign of other electrical problems in the car.


A Faulty Connection

Common Reasons Why Car Stereo Won't Turn on - Faulty Connection

But there are exceptions. For example, the wiring of an aftermarket car stereo should be different from that of an OEM stereo. Some stereos even have as many as six pieces of wiring.

Consult the user manual that came with your stereo to ensure if the wiring is connected right. The problem you’re facing here is that the car stereo won’t turn on despite having power. So in this case, the issue here is probably not with the wiring, but with the connection.

If you’re absolutely sure that the radio has power, then the next thing you need to check on is the connection. To do this, use a multimeter to check the power at the back of the radio.

If you see that the main unit does not have power but the black wire has, then that is the root of the problem. Trace the power wire and see if it’s working. Also check if that wire leads to a fuse that may have blown up.

Before moving on to further inspection, you need to check if the pigtail connector is connected properly to the head unit. If you have any doubts about the pigtail connector, simply remove it and replace it.

Just make sure that it is seated properly. If your installation has an adapter that connects the head unit with the factory wiring, then you can also try unplugging the whole thing. Just reconnect it this time being extra sure inside has good electrical contact. Then try powering it on.


The Issue Might Be a Poor Head Unit Ground

Common Reasons Why Car Stereo Won't Turn on - Poor Head Unit Ground Loops

Although a poor head unit ground usually causes minor inconveniences such as ground loops, but it sometimes can lead to a total failure. So, it’s only wise to also make sure that the head unit has a good ground before you cross out the entire unit.

There are a handful of ways of doing this. Starting from simply taking a good look at the ground and see if there is any rust in the ground. If it is connected tightly enough, to checking the ground between the head unit and the pigtail.

Most of the times, a poor ground will not bother you to the extent that the head unit will fail to turn on altogether. But a good ground that has gotten disconnected somehow, surely can.


Don’t Overlook the Head Unit

Just because it’s the head unit, doesn’t mean you have to go easy on it when it comes to getting the best out of your car sound system. A faulty head unit is as much replaceable as a worn-out seat cover.

It was good once, but now it’s gone bad so no need to show it any mercy. It might sound harsh, but having a head unit that doesn’t work is as good as having no head unit at all.

For a last resort, you may try bench testing the unit by connecting the ground and power leads straight to a 12V positive and negative, but if they both show good in the vehicle, it is probably the head unit that’s at fault. If that’s the case, then maybe it’s time to replace it and get a new one.


Other Accessories

Common Reasons Why Car Stereo Won't Turn on -amplifier connection

Sometimes an amplifier connected to the head unit also causes problems. Sometimes, it’s the wires that have been dislodged, often due to accidents such as bumps on the road, or even a new installation gone wrong. If you have installed an amp only recently, then check the wirings and see if you find any damage or misplacement.

Or it could even simply be that you plugged your CD player to the main audio unit and accidentally blew out a fuse. That also might cause your radio to not turn on. In that case, the drill is the same. Just replace the fuse, and you’re good to go.


What If the Problem Is Not Inside the Car?

Reasons Why Car Stereo Won't Turn on

This is very unlikely to happen, but it sometimes does. If your car has a remote control, and you have it switched off, then the stereo won’t turn on no matter how hard you hit the ignition.

This could also mean that the issue is not with the car or the head unit or even the remote control, but the power button itself. Maybe it got damaged somehow or temporarily stopped working for some reason. It could even be some kind of connection problem.

Whatever it is, a good thorough inspection is what should lead you to the root of the problem.


Some Extra Tips and Tricks

  • While you’re at it, always remember to cover your probes with the protective rubber caps to prevent a short circuit from happening.
  • Don’t rush it. Take enough time to examine the wires thoroughly and closely.
  • If you’re facing difficulty identifying and locating any particular wire or wires, or if you just want to testify that you’re doing things correctly, use the manual that came with the stereo. It has a detailed map of the entire wiring and all instructions and plans that you might need.
  • The manual of the car contains the location of the fuse box and a detailed graphical demonstration of the function of each fuse. Consult to it if necessary.


Some Final Words

These are the most common problems and causes that you are likely to encounter with your car stereo. After going through each of the steps described here, if the problem still persists, then the problem might be in the car itself. Then it’s best to take it to a mechanic.