The alternator in the Lexus Es300 is a generator that charges the battery and provides electricity to power all of the many electrical components of the vehicle. Over time, this generator may fail. There is no absolute lifespan for this part, though you should check it every 60,000 miles (most auto parts stores will check the alternator for free). When your alternator fails, you'll need to remove it so that you can either rebuilt it or replace it.
Look at the front of your engine and examine the drive belt configuration. Draw a diagram of your alternator and drive belt orientation. Look at the front of the engine and draw the orientation of the belt, and how it is woven through the pulley system with pen and paper. You will need to reinstall the belt in the same orientation.
Release tension on the drive belt. Place a socket wrench over the center pulley on the engine and turn the tensioner counterclockwise. This removes tension on the belt. Then pull the belt off.
Remove the upper and lower alternator mounting bolts.
Unplug the electrical connector on the back of the alternator and pull the alternator off the front of the engine block.
