Educated used-car buyers know it's important to test-drive a vehicle before making a purchase, as well as to have it thoroughly inspected by a professional mechanic. Edmunds.com provides guidance on what to look for when buying a used car, and most auto manufacturers offer online certified pre-owned vehicle inspection checklists.
But rarely does a used-car shopper put the audio system through its paces during a test-drive — other than maybe just making sure it turns on. And a buyer may typically turn off the radio in order to listen for unusual noises from the engine or drivetrain.
Yet an in-car entertainment system may be your constant companion while you're behind the wheel. Before you buy, you'll likely check that the seats are comfortable, the pedal positions are a good fit and the controls all work. So it's only prudent to take the audio system for a spin, too.
By taking a few minutes to pay attention to the stereo system, you can get an idea of the performance and condition of the audio components — and possibly avoid disappointment and costly repairs down the road. The testing is easy and requires no special tools other than your eyes and ears.
Do a Visual Inspection
While checking out the exterior of a vehicle, pay attention to the radio antenna. Is it broken, missing or barely hanging on? If the car has a power antenna, does it work? Or is it permanently retracted or extended?
While checking out the interior, make sure the radio, speakers and speaker grilles are in place. Check to see whether these items are poorly installed and if any obvious parts are missing.
It's quite common for someone to remove an aftermarket sound system when trading in or selling a vehicle. And even if the original owner doesn't do so, a dealership will often take out aftermarket electronics, according to several dealers we spoke with. Dealers prefer a factory appearance for their used-car inventory. They also don't want to tempt thieves by leaving aftermarket electronic equipment on the lot after hours.
Look for Telltale Signs
You can check to see whether a different audio system was previously installed in a vehicle by looking for such telltale signs as aftermarket wiring for amplifiers and speakers that have been left behind. It can also be obvious when inexpensive, low-quality equipment was installed just to fill the holes left by previous gear. Look for ill-fitting car-stereo components or mismatched speakers.
If you suspect that a system was previously installed, you may want to look behind trim panels, under the dash and in the trunk for possible damage to the car. Stock wiring and parts like panel clips could have become a casualty of an amateur or hack installer. There also may be unplugged screw holes that could leak fumes or water into the vehicle, or metal panels that may have been cut to install larger speakers.
To gauge the age and condition of the speakers, get a good look at them either through the grilles or from inside the trunk, if possible. Speakers often deteriorate from sun exposure when they have been installed on the dash or rear deck, and door speakers are susceptible to water damage. Keep an eye out for small, brittle pieces of foam and other material that can fall from speakers. If the speakers have deteriorated that badly, you may be replacing them soon.
Take the Systematic Approach
Making sure the audio system operates as it should only takes a few minutes and is easy to do if you follow a systematic approach. First, power up the head unit to verify it turns on and creates sound. If there is a power antenna, make sure it operates properly.
Next, check to see whether the head unit display works the way it should. Then turn on the headlights and see if the backlighting also illuminates. Be sure to check the clock and radio presets to confirm they are working, and give radio functions like seek and scan a quick check as well.
Now, perform a simple check of all speakers individually at normal volume to narrow down possible problems with a bad speaker or amplifier channel. Start by fading the system all the way to the rear, and then move the balance all the way to the left and then to the right. Then fade the system to the front and repeat the process. If the system has a multi-component speaker setup, such as a speaker in the door and a separate tweeter in the dash, you may have to put your ear close to the tweeter to verify that it's operating.
Bring along a CD that you're familiar with to check CD player functions and then give the system a good listen at normal volume levels. If the head unit has an auxiliary input, iPod integration or such functions such as video or navigation, it's a good idea to give those a quick check as well. This is also a good time to ask if an owner's manual is available for the car or the system. This lets you familiarize yourself with the features.
Perform a Sound Check
With the basic functions checked, you can move to an actual "sound check" of the audio system. First, perform a radio reception test to make sure the radio tunes in the stations it should. This is really nothing to get worked up over unless there's zero reception.
Start the engine and listen for any engine-related noises coming through the speakers, such as whining or ticking sounds that change with the engine rpm. If such noises are present, poor wiring or a defective component may be the culprit.
Next, listen to the system with familiar music. Use normal volume while parked and louder volume while driving to see how the system performs with road noise. Listen closely for any speakers that sound distorted or are making crackling or scratching sounds. In most cases, this indicates a blown speaker, although it's also possible that distortion could be coming from other components in the system.
Finally, ask yourself whether you will enjoy this sound system over the long haul, or whether a post-purchase trip to a car stereo store is in your future.
Use Problems as Leverage
Problems you discover while test-driving the audio system on a used vehicle may not ultimately make or break your purchase. However, you may be able to use any problems you find as leverage for negotiating a lower price, or free or discounted repairs if you're buying from a dealership.