topdog849

iTrader: (1)

i replaced my alternator back in december and again around may along w/ a new battery(still gotta fix leaky distributor.) but still my car keeps dieing while driving every once awhile and i have to go back to advance auto zone to charge my battery. the battery light always stays on and when i leave it in neutral it starts to flash. i just came back from autozone and had them test the alternator and it seems to be fine. someone please help me before i get fed up and sell my lexus or put a bullet to my head.

madmax98

Well, if your car dies while driving, that means your car isn't getting any power which means your alternator is bad. when the alt. is bad the car will go on for a bit of the battery juice till it dies then your car dies. Now if the alternator tests okay < and you're absolutely positive it's fine> test the connections to the battery, clean up the poles, and while you're at it just get the Optima. Also, i'm assuming you don't have a killer audio system. If you do, then you now know where the problem is.... goodluck...

over40driv

When I bench test alternators I always incorporate a charge light in the testing. An alt. can charge but not turn the light off, which means some part of the alt. is compromised.

madmax98

If i were you, i would go right now and try to start the car: if it starts right away and sounds strong then your battery is fine. Then i would disconnect the cables < carefully and for a short amount of time> while the car is running and test the voltage between the 2 cables < remember: No battery> and see if it gives at least 12 volts: If it does then your alternator is also okay. At this point, it has to be something else like connections or loose dirty cables...

topdog849

iTrader: (1)

ive been told not to disconnect the battery while the car is running because it causes voltage spikes that can damage the ecu

over40driv

I recommend only checking the voltage at the battery with a volt meter with both cables attached.

madmax98

That's true if you run for a prolonged period of time, few seconds won't hurt, also alternators have voltage stabilizers built in as i recall...

topdog849

iTrader: (1)

im going crazy searching trying to find an answer. whats a voltage regulator? could that be the problem? anyone ever replace one?

over40driv

The voltage regulator is built in the alternator.

topdog849

iTrader: (1)

i feel stuiped now. the only thing i can think of is maybe the wiring from the alt. to the battery is corroded or something but idk how to go about replacing that. i am so close to trading my sc for a 240 ; (

JspecSC3

iTrader: (4)

If its still on the something is still wrong. Either the alternator is not producing enought current or your batter is dying. I'd get them both checked out. I know you just replaced your alternator not too long ago but I had the same issue where my 4 month old alternator had gone bad after a rebuild. Good thing it was still under warranty.

madmax98

Dude, it's actually a very small problem that requires simple troubleshooting. just be patient and start troubleshooting, you already know what to do, so go do it.... GL...

LEXUSC-400

On a sc300 with a leaky distributer o-ring the oil leaks directly onto the altenator which will cause it to wear out very quickly. If it's the sc400 then it's not related. Hope this helps

topdog849

iTrader: (1)

problem still not fixed. i found this supra article on the web
http://www.mkiv.com/techarticles/4ga...lead/index.htm
im thinking this might fix it but not for sure. i know its the same engine but the fuse box looks totally different. does anyone know where i should connect the new cable in the fusebox?

TheMole

iTrader: (13)

Agreed. The leak from the distributor o-ring onto the alternator can slowly kill it. Do you notice any oil on the alternator?
You can also check the engine grounds so you can rule them out.