Listening to your favorite tracks in the summer with the windows down can come at a cost. Speakers can burn out the best audio system over time. It depends on what you listen to and how loud you hear it. A lot of heavy electronic music and rap are notorious for blasting out speakers at the correct volume.
Steps
Part 1 of 4: Hear the damage

Step 1. Start the vehicle
Most vehicles must be turned on for the audio system to work. Unless the car is private, you will not have to fully start the engine, as it would only waste gasoline.

Step 2. Insert a CD or MP3 device with full sound range
Pick something that you usually play in your car, so you know what to listen to. This will help you detect if any of them sound weird. You could also listen to a song that has a clear, familiar bass line.

Step 3. Increase the volume to an appropriate level
If the audio is too low, it will be difficult to tell if there is a burned out speaker. This does not mean that you have to overwhelm the entire neighborhood with music to diagnose the vehicle.
Adjust the treble and bass if necessary. Make sure the levels are the same at the twelve o'clock position. When you hear a lack of range, it could mean that the system is not equalized properly

Step 4. Recognize the distortion
If you have trouble recognizing distortion, play a track on your headphones or another device. Then play the same track on the car's sound system. If you hear crackles or the song sounds slightly muffle, one or more of the speakers may be burned out.
Hear the rattle. If the speaker is burned out, you may hear a shaking and rattling sound

Step 5. Listen to the lack of reach
If a certain low, medium or high horn is burned out, you will notice that certain registers do not come out. This is easier if you are familiar with the song and know what to listen to or what to expect.

Step 6. Isolate the speaker
If possible, use the system's attenuator controls to try to isolate the faulty speaker. By reducing a section of the car, you will have a better chance of determining which horn is burned out. Always try to isolate the problem so you don't overspend and replace the entire system.
- Use the scroll function to change the sound from left to right. When scrolling, go either 100% left or right to isolate the sound completely.
- Use the attenuation settings the same as the offset settings. Go 100% to the back or front of the car.
Part 2 of 4: Test the connection

Step 1. Remove the cables from the amplifier and connect them to a 9-volt battery
Hear a short blast from the horn.
- You may have to unscrew the horn from its bracket.
- Only remove the cables if you are comfortable handling electronic equipment.

Step 2. Check the horn
Remove the speaker cover so you can check it. Connect the wires to a 9-volt battery again and watch the horn. If the cone moves, the problem is with the connection, not the horn.

Step 3. Get a multimeter tester
These simple electronic tools help measure ohms and voltages. You can buy them at local electronic stores or hardware stores.
You can also use an ohmmeter

Step 4. Test the ohms
Set the device to read ohms if you are using a multimeter. Make sure the speakers are off. Touch the device wire to each speaker post. The post is the part of the speaker where the wires meet.
- If you get a 1.0 ohm reading, the speaker isn't burned out and the problem is elsewhere.
- If the device reads infinite ohms, it means the speaker is burned out.
Part 3 of 4: Test the Amps

Step 1. Understand how bad amps can affect sound
If there is something wrong with the amplifier, you will likely hear some sound distortion when you turn on the speakers, or hear nothing at all. Usually it is because there is something wrong with the fuse or with the capacitor.

Step 2. Open the fuse box
If you don't know where the fuse box is, you can check online or in the manual that came with the car, as each one will be a little different. Generally, a fuse box is located in the front where the knee rests or under the dashboard.

Step 3. Take out the multimeter and set it up for the conductivity test
This will help you find out if the fuse is good or not.

Step 4. Connect the multimeter to the fuse box
Attach the red lead from the multimeter to one of the fuse posts. Put the black wire from the meter to the other terminal.

Step 5. Listen for beeps
If you hear a beep, it means the fuse is good and the problem is likely with the capacitor. If you don't hear a beep, the fuse may be blown and needs to be replaced. Make sure you get the exact same model of fuse.
If you hear a beep, consider replacing the amp first. It is generally less expensive and does not require soldering irons or desoldering pumps like the new capacitors

Step 6. Start the car and test the speakers
They must work now. If they don't work, there may be something else wrong with the car's speakers. Consider taking the car to the shop and having it inspected by a professional.
Part 4 of 4: Determine the extent of damage

Step 1. Inspect the damage
Look at the horn once you determine that it is the faulty one. Look for holes, tears, or divisions in the speaker. Make sure the speaker cover is off so you can check it thoroughly. Most of the damage you can see will be on the horn cone or soft part.
- Gently run your hand over the cone to make sure there are no scratches that you can't see.
- Dust or dirt shouldn't affect the quality of the speaker, but it might be a good idea to clean it.

Step 2. Repair minor damage
If there is only a small scratch, you can repair it with a sealant designed for speakers. If the damage is great, you may need to replace the horn.

Step 3. Test the remaining speakers
Once you determine that one of the speakers is burned out, you should see if any of the others are as well. Remove the faulty speaker if you haven't already. Play a track and listen to the irregularities of the speaker.
- If the problem persists on multiple speakers, consider replacing the entire system.
- Follow the steps above to test another questionable speaker.

Step 4. Let a professional review
Take the car or speaker to an automotive audio specialist. Explain the tests you did and ask him what his estimate would be for checking and repairing the speaker (s). Be honest and ask him if he thinks it would be more profitable to replace the entire set.
Warnings
- Always practice electrical safety.
- Never put tools or other objects in a speaker that is still connected to the power.
- Be careful when working with anything electrically charged to avoid injury.