To change an alternator, disconnect the battery, remove the serpentine belt, disconnect electrical connections from the alternator, unbolt the alternator, and replace it with a new one. Plug in the battery, and test the installation. You need a socket or wrench set, a digital multimeter, and lubricant spray to complete the project.
Switch off the engine, open the hood, and unplug the negative cable from the battery with an open end wrench to prevent electrical shock. Unfasten the serpentine belt, and pry it off the pulley. Take a picture of the wiring harness behind the alternator before you remove the wires. Loosen the alternator mounting bolts with a wrench, and remove the alternator.
Take the old alternator to an auto parts store, and purchase a new alternator. Attach the replacement alternator to its mounting position, and bolt it in place. Use your photo to reconnect the power and ground wires to the device. Reinstall the serpentine belt, pulling the alternator until the belt is tight. Replace the belt with a new one if it is damaged.
Once the belt is tight and set to correct tension, reconnect the battery. Start the engine, idle the engine for about three minutes, and use the electrical output indicator to confirm that the new alternator is functioning properly. Alternatively, connect the digital multimeter to the battery terminals, and start the engine. The output on the multimeter should read approximately 14 volts.