I have a 2008 RX 350. Never had a problem with it. Today as I was driving, all of the warning symbols flashed on the dashboard and then the car died. Had it towed to a local Lexus dealer. They said the alternator was the problem. Here is my question: should a warning light for either the alternator or the battery have come on prior to the "breakdown"? And two months ago, it had its 90,000 mile service and apparently the electrical system/alternator looked good OR the technicians missed something. Anyone have any thoughts or opinions?

 

It probably just died at that moment, hence no warning. If it will start now an easy way to test if alternator is working is to start car, then carefully remove negative battery terminal from battery. If car dies, alternator is bad. Some last longer than others, just depends on use, but one thing that will kill an alternator is liquid contamination from leaks. Inspect the area for fluid leaks too. Power steering, etc. Look closely at your serpentine belt to see if it has any fluid wetness on it.

 

Most likely a Diode died in the Alternator, with a Multimeter tests can be achieved....
http://easyautodiagnostics.com/misc-...d-alternator-1

 

There should be a battery light that will come on if the battery voltage is too low. Problem is, I recall the threshold is pretty might right when the voltage is low enough to kill the car so you'll see it and then usually the car dies right after. Only way to really know if your alternator is failing is to use a voltage meter whether a multimeter or ones that you install for stereo systems that connect directly to your car's switched 12V.

 

Thanks for the responses...particularly that from BlackLexRX. The dealer's manager called me an hour after the car was towed to the facility. He said that the alternator can go bad and fail instantly with no prior warning and that even though his dealership did the thorough 90,000 mile service and inspection two months ago, there was no way that the technician would have known the alternator will soon fail like it did. He said it tested in the normal range two months ago. BTW, he first quoted $1000 to replace the alternator. Then offered to reduce the price to $500.

 

You can get one from wrecking yard, buy rebuilt one, or have yours repaired. Sudden failure is typical behavior of any electrical component. In this case it is lot easier to find the problem. Partial failure which causes intermittent nagging problem is the worst to trouble-shoot which leads to wasted time and parts until real culprit is nailed.

 

Usually as I posted a Diode can fail therefore most parts stores offer new rebuild alternators (as starters also) although you have to give your old alternator as a trade in, if you have a reliable honest mechanic, he knows this & your bill will be much less than $500., obviously your RX isn't under warranty....
of course your dealer will drop the price, still plenty of profit to be had at $500. since they will most likely drop in a new rebuilt alternator & you will never know the difference, as they appear brand new & will function perfectly for years to come..

 

Modern alterantor for cars are 3 phase AC generator and AC current is rectified by a diode bridge to output DC current. Alternoator failure could be mechanical like bearing or bushing failure orctrical like, diode bridge module failure partial or total. Some times diode failure is due tio too much heat. Diodes with heavier specs. can be used.

 

I see them at about 175$ rebuilt, so you could do it yourself with a new belt for around 200$. 500$ at the dealer while pretty stiff is probably on par for what they do and fair under their pricing (175/hr labor or whatever). If you can afford it, that seems pretty fair considering they cut their price in half, they will do it right and guarantee it for at least a year. If your dealer is like mine, they'll give you a 2016 or 17 to drive around for a day, wash and clean your RX, and fill it with gas. Your local indy won't offer that, but might save you 150$ or so. Is it worth another 150$ for piece of mind and a few perks? That is the question.

 

Rebuilts are reliable alternatives. There are certified factories who rebuild these. They are actually scrutinized heavily, specially if they are an authorized OEM rebuild factory, means they carry the same label as OEM, like Denso, etc..

 

did you go with a new or rebuilt?