Diagnosing your Buick alternator can be tricky because a failing alternator can present a whole host of different symptoms. In addition, a failing alternator will fail gradually until all electrical accessories in your car will not work and your car finally dies. The Buick alternator's job is to run the car's electrical system and recharge the battery, enabling the battery to start your car. The alternator is driven by belts in the engine, where it produces an alternating current, which is converted internally to 12 volts direct current by the diode bridge or rectifiers. When the alternator begins to fail, the car might run off the battery's stored energy, until the battery dies. It might take some detective work to determine the problem at first, because diagnosing electrical problems in any car can be tricky. One sign: the charge indicator light (or 'idiot light') comes on, although that may also represent a faulty fuse in the system, and not a bad alternator. You can check the voltage at the alternator connector and other connections in your electrical system with a voltmeter to measure the voltage. Or, listen for a distinctive grinding noise that comes from the alternator's bearings. All of these may be signs that your Buick alternator has been finally been worn down by the demands on the car's electrical system. Because of the demands of new electronic accessories, alternators face new stress from this system overload - so replace your Buick alternator at the first sign of problems and save yourself from replacing a battery as well.