A: The alternator is operated by a drivebelt turned by the crankshaft pulley. The rotor turns inside the stator to produce an alternating current, which is then converted to direct current by diodes. The current is adjusted to battery charging needs by an electronic voltage regulator, which is controlled by the logic and power modules.
A: Due to the specialized training and equipment needed to test and service the alternator, it is recommended to take the vehicle to a dealer or repair shop with the proper equipment if a problem arises. The most obvious sign of a problem is the alternator warning light on the instrument panel coming on, particularly at low speeds, indicating that the alternator is not charging. Other symptoms include dim headlights and the starter motor turning the engine over slowly, indicating a low battery state-of-charge. The first check should always be the drivebelt tension, followed by ensuring all electrical connections are secure and free of dirt and corrosion. If the drivebelt tension, electrical connections, and battery are good, an internal fault in the alternator or voltage regulator is likely. Due to the specialized tools and techniques required, diagnosis and repair should be left to a properly-equipped shop. If the vehicle has considerable miles on it, a good alternative is to replace the alternator with a rebuilt unit.
Q: What Maintenance is Required for an Alternator?
A: The alternator requires very little maintenance because the only components subject to wear are the brushes and bearings. The bearings are sealed for life. The brushes should be inspected for wear after about 75,000 miles (120,000 km) and the length compared to the Specifications. Regular maintenance consists of cleaning to remove grease and dirt, checking the electrical connections for tightness and adjusting the drivebelt for proper tension.
Q: What Precautions Should Be Taken to Avoid Alternator Damage When Working on the Electrical System or Using a Booster Battery?
A: When working on the electrical system or using a booster battery, ensure the battery cables are never reversed and the negative cable is grounded. Disconnect the negative battery cable first when removing the alternator or disconnecting its wiring. Never operate the engine with the battery-to-alternator cable disconnected and observe correct polarity.
A: With the ignition switch in the Off position, disconnect the negative cable at the battery and place it out of the way. Disconnect the alternator wires, marking each wire and terminal for correct reinstallation. Loosen and remove the drivebelt by loosening the adjusting and mounting bolts. Remove the mounting/adjusting bolts, followed by the pivot bolt and nut to separate the alternator from the engine. To install the alternator, place it in position and install the pivot bolt and nut finger-tight. Install the drivebelt and then the locking/adjusting bolts, adjusting the drivebelt tension and tightening the locking bolt. Finally, tighten the pivot bolt and nut.