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How to Troubleshoot a Dead Sub Car Amplifier

Learn how to troubleshoot a dead sub car amplifier in this Howcast car stereo video with expert Movin' On.


Hi my name is Movin On, and I've been working in the field of car audio and mobile electronics for 8 over years. I've installed everything from navigation systems to full car stereo systems, remote starters, alarms, and beyond. To learn more, visit our web site at

One of the most popular add-ons for a car stereo is a subwoofer/amp combo. Because of that we have a lot of people coming in with problems and they want to see why their subwoofer is not playing. If you have a sub/amp combo that is dead, one of the first things that you should check is the fuse under the hood. Pop the hood, look near the battery, and there should be a big power cable coming off of it. Usually red or blue or some easy to notice color. Often times it is going to be covered with wire loom, which is usually black. Check for the fuse, which is usually going to be six to twelve inches from the battery, and see if the fuse is blown. You can usually tell if it is blown because the piece in the middle is going to be split apart. If this fuse is blown, it means that there is a problem back by the amplifier, or you might have just played it too loud and it overheated and drew too much power. If your fuse is not blown, the next thing you are going to do is check the amplifier itself. Usually there is a protection light on the amplifier that is going to go on and put the amp into protection mode if there is something wrong with it. Usually it is labeled on the side of the amp what color this light should be if the amp is in protection mode. If there is a short at the amplifier, often times the fuses on the amplifier itself will blow. This is not to be confused with the fuse that is underneath the hood that powers the amplifier. The fuses that are on the amplifier protect the amp from a shorted subwoofer. If you check these and they are blown you are going to want to check your subwoofer next and make sure that it is not shorted out. Another good thing to do is check your grounds. The ground is the black wire that comes off the amplifier and gets screwed into the chassis of your car. If the ground is not good, you are going to have a problem. You can usually check a ground with a multi-meter or just use a factory ground. If you have another subwoofer that is available, you can simply plug it in to the amplifier and see if it plays. If that subwoofer plays and the other one doesn't, then there is something wrong with the subwoofer. Sometimes you can unscrew the subwoofer from the box, look inside, and check for a bad connection. Sometimes the subwoofer is not blown or dead — it is just that it is not connected properly.

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