I did a search and could find little relating to bad alternators in the Lexus cars. My charge light came on in the dash last week and then went off. I had the battery for about 4.5 years and had it tested at O'Reilly's and they said it was bad. Replaced it and the light stayed off for about 4 days. Yesterday the light came back on and has stayed on. The car starts and runs fine. I get 12.34 volts across the battery terminals with the engine off and 11.89 volts across the terminals with the engine running. This would lead me to suspect the alternator. There is no noise so I suspect the voltage regulator in the unit itself. Am I missing something?

 

Most likely your alternator is bad. You .can check if it is actually is bad with any auto part. You're now running the engine using your battery, soon your battery will die. Hope it won't be the time that you're on the road.

 

It was a bad alternator. I am surprised that it went bad this early. 06 with 118K miles. My 2000 ES and RX that are still in the family are on the original alternator. Oh well, this is the first thing to go bad on the car. I would say that is low maintenance.

 

I feel your pain. My '06 alternator went bad at 84k miles about 2 months ago.

 

Just wanted to add to the thread. I had to replace the alternator in my GS400 once due to a slow P/S leak at the reservoir. Because of the location of the leak it can take out the alternator, so be sure and pay attention to your power steering level.

When I purchased my SC430 a few months ago, I noticed the previous owner had their alternator replaced in the maintenance history. I dropped the car off at the dealer just to give it a once over, and sure enough they found a small leak near the P/S reservoir.

NOTED POWER STEERING FLUID LEAK FROM VACUUM VALVE. RECOMMEND REPLACING POWER STEERING PUMP VACUUM VALVE AND RESERVOIR HOSES AND HOSE CLAMPS.

Just something to keep an eye on!