2005 Lexus LS 430. Battery died. Replaced battery and alternator. Next morning, battery is dead. Replaced what mechanics though was defective with second Interstate.It is now drained and dead. I can't figure out what is wrong with the electrical system. Help! And thanks in advance.

Jack Hubbard

 

One light bulb can be left on and battery will be dead next morning. It is possible the trunk light is not turning off which is something you can't see. With everything off put an ammeter in series with the negative battery cable to see the draw. If over 75 to 100ma start looking for the problem and I would start with taking trunk light bulbs out and then the accessory fuse and so on till circuit is identified.

 

Definitely trunk light. Getting a new trunk latch. Light thought trunk was open when it was closed, thus doing exactly what said it would; drain the battery overnight. Thanks for the tip. You were spot on. Getting the car back tomorrow, Will report after the installation of the latch. Thank you for the assist. I didn't know how to diagnose the problem and was flummoxed.