Remember the days when your car audio system consisted of a single speaker mounted someplace in the dash board? Or maybe you had a really fancy system that had a speaker in each door - stereo! Ok, in all honesty I didn’t live through this era, either. The vintage Porsches that we work on in our shop have these simple car radios, and as a result they are super easy to troubleshoot if you have a problem like a crackly speaker or a speaker that just doesn’t work.


 

Troubleshooting a modern stereo system can be a monumental task. A car with less than six speakers is a rarity these days, and 12 speakers is not unheard of. Luckily you can use your ear to figure out which speaker isn’t working, so you’ve got a place to start. Before you can start to really troubleshoot, you need to know whether your vehicle uses remote or central amplification. 

Centrally amplified speaker systems

Every car audio system has one or more amplifiers, or amps, to boost the volume to the levels we desire. In a centrally amplified system, there is a single amp that takes a signal (in the form of music) from the stereo systems main controller (known as the head unit) and boosts it to all of the speakers. The amp uses a system of channels to divide the signal amongst the speakers — front to back, left to right, subwoofers, etc. Each of these channels leads to a separate speaker, but they are all powered by a single amplifier that is centrally located so that the massive spider of wires needed to reach each speaker can be run efficiently.

 

Remote amplified speaker systems

As car audio systems developed to the point of producing concert quality sound in the cabin of your car or truck, the demands on the car’s amplifier were multiplied. Eventually, audio designers started installing two amps, dividing the system into two power blocks. As the number of speakers grew, another amp was added, until we reached the point many systems are nearing today — each speaker has its own amplifier mounted on or very near the speaker itself. This method makes servicing the system easier, but it can make diagnosing audio system or speaker problems at home a lot more difficult. 

Testing an amplifier

The first thing you need to check when you've got a speaker out is the amp. You need to see if the amp is getting power (electricity). If you're super lucky, there is a light on the amp that's letting you know it's on. This is not likely. Unplug the wiring harness from the amp and, using the wiring diagram from your repair manual, find the wires on the plug for power, ground and remote and test them. If they are all indicating power, the next thing to check is the amp's output. You can do this with a multi-meter, or you can test the amp using a known-to-work speaker. For a detailed amp test, check out this tutorial.

Testing a speaker

If your vehicle uses a central amplifier (see above), you can use a very old-school method to test the speakers and the connection between them and the amp. Find a 9-volt battery, the old rectangular type that you used to run your head-to-head football game with. Touch the one speaker wire to the positive side and one to the negative side of the battery. You may need to use a jumper, there's no reason to cut any wires or destroy your plugs for the test. When you touch the wires to the battery, you'll hear static coming from the good speaker. I love this method! If you've got remote amps, you can still test the speakers with a battery, you just need to access each speaker separately.