Generally speaking, the Lexus LS400 is a reliable automobile. Regardless of how reliable a vehicle is, however, parts will wear and eventually fail. The alternator is responsible for delivering the necessary electrical power to all components that need it, so when it fails, you need to replace it as soon as possible. The good news is that replacing the alternator is not at all difficult. A person with no experience can do this project in less than an hour.
Disconnect the negative battery terminal. Use a wrench to loosen the nut.
Loosen the alternator pivot bolt with a socket and ratchet and push the alternator toward the engine slightly to loosen the belt. Pull the belt off the engine. Unplug the wiring harness from the alternator and remove the ground wire using a wrench to remove the nut.
Remove the bolts from the alternator using the socket and ratchet. There is the pivot bolt, and then a bolt at the bottom of the unit. Pull the alternator out of the car.
Put the new alternator in the car and loosely install the pivot and the bottom bolts. Put the alternator belt back on the car and pull the alternator toward the front of the car to pull the belt tight. Tighten the pivot bolt first, and then the bottom bolt with the socket and ratchet. Reconnect the negative battery terminal.
