TurbodVq35

So I've searched countless threads for a solution and have yet to find anything that could possible resolve the issue I'm experiening. So Saturday afternoon our 2nd car, a 2000 Lexus GS300 decided it didn't want to start. So I pulled out the jumper cables and jumped the car. The car ran fine for a little bit and started to die. I took the battery to Advanced Auto parts and they charged the battery to 12.5 volts and said the battery was good. Got back home installed the battery and the car started right on up. All set right.....NOT =(....the car died again. I take the battery out and return to Advanced where they gave me a brand new battery, as the old one is under warranty until 2018. I put the battery in and start the car up and let it run for a half an hour and it seemed fine. Turned it off and went in the house for the evening. Sunday morning the lady decided to go to church. She goes outside and the car doesn't start. So I jump it thinking the battery didn't charge fully. Later that afternoon she went for a short drive and on the way back home the car died again. I am now led to believe the alternator needed to be changed.So today I installed a new alternator and new battery. checked all the grounds and started the car. The car started to die again....WTF!.... changed the alternator again and got another battery....same thing. I've checked voltage on 1the battery and the alternator and it seems fine. But before I decide to go to a mechanic I wanted to know for those of you who had this problem, what caused it and how did you resolve it. I'm just trying to eliminate things before I decide what to do with the car. Thanks for your help guys

Mandrake

You could have a parasitic drain, the exciter wire is damaged or you're buying bad alternators and batteries Before accepting your return, wherever you got the alternator from should've tested the alternator and battery unless that was a junkyard. How many volts is the alternator putting out? How long did the car run between the second and third alternators?

You can check the fuse box for a parasitic drain. One method I heard is to turn everything off in the car and then hook a digital multi-meter up in series with the positive battery terminal (one probe to the battery cable, other probe to the positive battery terminal; in series) then check to see how many amps DC you're draining. Should be less than 1. If its like 1.5, start pulling fuses and checking. If you find one particular fuse, for the radio for example, that causes the amps to drop to like .25 when removed, then you have a parasitic drain on that circuit.

Basically it sounds like this is an electrical problem and you need to bust out the multimeter to get anywhere.

BiGEZ

iTrader: (24)

Check you battery cables to ensure the are in intact. My buddy had that same issue on his SC300 turns out to be a bad negative battery cable. Just throwing that out there as a possible cause.

MotoCARR

2nd on parasitic drain. Check out this video

TurbodVq35

BIG UPDATE!
So for those of you that haven't come to a resolution here are a few things to check:
1. Alternator fuse-located under the hood in the fuse box by the battery. (It's 7.5)
2. AM1 fuse (I'll explain this to you later)
3, All cables that go into the fuse box by the battery

So after testing all the fuses in the fuse box by the battery, I found that one side of the alternator fuse had a short which was causing the alternator not to charge the battery. Upon inspecting the fuses I had removed the bad ABS fuse (shop broke the fuse and there were only two prongs and never screwed the 8mm and 10mm screws back to the post). So after changing the alternator fuse I get in and the car starts right up! All done right......NOT....Now the dash, has no lights, no radio, no power windows, no power seats, no sunroof.....WTF!..... check the AM1 fuse by the drivers side kick panel and everything is good. After testing all fuses, I come to find that the fuse box below is getting no power. After 10 minutes of tracing back what I did something said go buy the ABS fuse and put it in. I do that and wella...problem fixed. It seems that the fuse box located on the drivers side kick panel gets power from the wire connected to the ABS fuse from the fuse box located under the hood. So for those of you that have the "NO POWER IN THE INTERIOR", this is something to check. Nonetheless, car is up and running like normal.

BiGEZ

iTrader: (24)

Glad you got if figured out, electrical issues are a royal PAIN.

Winslow96

Just went through a cold snap where i live and mine wouldn't start sometimes now (even though its warm now). Did a voltage test and got these results:

13.10 V @ 3000 rpm (No load test)
​​​​​13.78 V @ 2000 rpm (Loading test).

I've hear 13.0 V minimal can be acceptable in some cases. What do you guys think? Is this alternator ready to go?