Troubleshooting Hour System

According to Murphy’s Law, things can and do go wrong. That’s especially true with a car audio system. With so many separate components and so many wires running to so many places, it’s surprising that car audio systems work as well as they do.

Although there are fixes for these various problems, it’s always easier to take preventative measure to stop noise before it starts. (Remember the old “an ounce of prevention is worth a pound of cure” thing?) In this case, prevention means making sure your components are properly installed, wired, grounded, powered, and maintained.

But if you do run into a noise problem, there’s usually a solution. The next few sections cover the most common problems that can plague a car audio system and how to fix them.

Grounding problems

Most problems that can’t be directly attributed to a faulty car audio component are usually due to improper grounding. With improper grounding, the connection in a circuit is not at the same potential, meaning that the circuit sees a different ground, and this can cause noise. (I cover grounding in more detail in Chapter 18.) Start by ensuring that you have a good ground for all of your components, particularly your amplifiers. With amplifiers, the ground wire should be connected to the chassis and the ground wire should be the same size as the power wire. In addition, power connections at the battery should be checked to make sure they are solid.

The negative battery post is never a good place to ground car audio components: It invites noise into the system.

Alternator whine

Alternator whine is the most common and one of the most difficult system noises to stamp out. It’s a high-pitched whine that varies with engine speed and is usually caused by a bad ground.

You can eliminate it by grounding the offending equipment directly to the metal chassis of a vehicle instead of a factory grounding bolt. Also, ensure that your charging system is working properly and that the connections between the battery and your car audio components are secure. Another possible fix is to change your RCA cables from coaxial to twisted pair.

Switch pop

Any vehicle accessory that draws high current can cause a spike in voltage in the car’s electrical system, which in turn seeps into the wiring of your car audio system and is heard as a pop. A switch pop can usually be traced to turning on or activating a particular electrical accessory in a vehicle: brake lights, turn signals, headlights, windshield wipers, or the air conditioning.

Professional installers typically add a small capacitor between the accessory’s power wire and ground to soak up these errant power surges and hence eliminate the pop. If you sometimes hear a switch pop on your system, seek out a shop or installer that deeds with such problems.