Need some advice,

Ive replaced the battery 2x within a year, dont have a sound system only modification are HID headlights.

I do notice that the lights are dim when car is at a stand still, everything gets brights when the accelerator is pressed; even the AC pumps harder when gassed.

This morning the car barely turned over but by some miracle powered up. I reverse down the driveway when i put it into drive and press the gas it felt like the tranny was slipping; RPMs rising but no movement then it locked and went. FIRST TIME this has ever happened. The car has never slipped. EVER.

Is all this related? alternator battery?

Any input would be great!
2002 GS300 110k

 

I would check the battery cable integrity first. Whats te voltage you are getting currently?

 

The tranny needs powah! This too was happening to me.

First off, to fix the tranny thing when this happens, put it in reverse and step on throttle, give it a little umph! it resets the tranny. When battery goes dead, it resets everything and tranny needs to learn how to work again.

You kinda answered your own question, you've already tried the battery, so most likely its the alternator. The position of the alternator is in a place where an oil leak (in the right place) will saturate the alternator and make it go bad, that could be on issue, or the obvious would be just the age of the car Remove it and get it checked. I think the alt and battery are taking each other out. Once you get a new or repair the alternator, be sure to fully charge up the battery.

A damaged alternator can kill a battery, so the fact that you've gone through 2 batteries shows that could be the problem. Could be something simple as a busted diode. Also, if the alternator isnt producing enough charging voltage, that can run a battery down. Get a meter and check the voltage output on your alternator at idle.

 

I think your stereo system is the problem. It probably has a voltage draw on it, which is running the battery down. If it were the alternator, then battery would have died days after you put a new one in.

 

^^ Nope.

and he doesnt have a system.

as I stated, a simple thing as a diode (which regulates which way current flows) goes out, the alternator can discharge [overnight] the battery. Batteries arent made for constant [complete] draining and charging unless its a deep cycle battery, in time that can kill a battery. Just because a diode is out, that doesnt stop the alternator from doing its job. Reason lights are dimming is because now theres not enough storage in the battery to keep up with the cars demands. HID's arent helping either, they take a LOT of juice to run. (and thats all just a nut shell of information. No need to write an essay) Other reasons for the problem are wires arcing somewhere causing the battery to keep draining over night, but his car is all stock, so doubt thats the reason. When the battery under my hood (I have 4 total) began doing the same thing (also lights dimming and a/c going up and down with throttle) I would turn my HID's on and the alternators output would drop by 1.5v, thats a lot! Now that I replaced the battery, it doesnt drop at all. <-- that story is to support why his lights are dimming etc. My battery problem is not the same as the OP's though, my battery was killed due to a loose wire contributing to constant overnight draining.

 

@GS4 AND 2GS Thanks for th input. deeply appreciated.
@MrJokster
I will change the alternator. Any suggestion on whether to go with an OEM replacement or aftermarket? How do you feel about recertified? How can I check Diodes?

Thanks again to all for the support with this.

 

OOPPS...mis-read. He doesn't have a system.

 

I wouldnt change it just yet. You can take it in to autozone or kragen, they have a machine they hook it up to and they put a 'load' on it. That test should clear it all. I'm not certain it sends and retrieves current to check the diode.

I'd go OEM. Reconditioned or "recertified" I wouldnt do, they dont use the same strong wires to wind they coils and in my opinion not up to par of OEM. I personally have a friend who makes the reconditioned ones for part stores and I've had mine rebuilt and am yet to have a problem (if thats any consolation). If you can find someone who rebuilds them, our alts can actually produce 140a (as opposed to the factory 100a) Alternators are shared among many makes and models and when I took mine to my bud, he said its the same one off [I think] the dodge caravan, which has a 140a. So he built mine up to 140a and its fantastic (still not enough for me though )

 

Oh and, not sure what year and model yours is, but the 300, 400 and 430 all have the same alternator. Here's where you can buy the parts to rebuild yours:

http://lexus.sewellparts.com/oem-cat...S430-2005.html

I'm surprised to see Lexus selling a rebuildable part.

 

oh AND

If you plan on putting a system or any other electrical load, you're better off going with a high output alternator like from DC Power, Mean Green, Iraggi etc. They're the same price as oem and you get a MUCH better alternator I recommend DC Power. I'm not sure about the others (probably do too) but DC Power uses Gold internals for great conductance and great for heat

 

What is the Voltage of your Alternator output? Should be ~14v

Check the cables, if you've changed your batter a few times, the battery terminal is known to stretch and not give a good connection. I've had to change my terminals before too.

Check your grounds, make sure they're clean and not corroded.