Hi all,
My 2008 IS250 has been having battery draining issue for a while. I could not rule out the source of the problem yet. If I park the car for 2 days or more, the battery will completely running out of power. At first I thought it was the battery so I bought a new one. It did not resolve the problem. :
From the battery positive post, there are two electrical wires connect to it, one connect to the alternator and the other connect to the fuse box. To verify if the alternator is the culprit or not, I disconnected the wire that is connecting to the fuse box, only left the wire that connect to the alternator. see image below:




I then measured the voltage (12.25 volt) and let the car parks for two days. If the voltage does not drop significantly, can I assume that the alternator is not shorted?
I will do the fuse removal and measure the current next if I know the alternator is good.

Thanks everyone in advance!

 

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You might want to clean the corroded battery posts first. Check if all the interior, trunk light, dome lights, vanity light, stereo are off along with all the gadgets, phone chargers, players, dashcam, GPS, seat warmers/ seat cooling fans etc are all off...

 

 

Thanks, Primavera! I already checked all of the above. I am thinking it might be the alternator that is draining the battery. I want to know if my method of checking the alternator is valid???

 

Thanks, MikeFig82! I already followed the video you sent but could not find anything. I am thinking it might be the alternator and want to verify if my way of testing the alternator is valid?

 

You can find some answers here:
https://axleaddict.com/auto-repair/A...g-System-Tests

 

[QUOTE=MikeFig82;10855397]You can find some answers here:
https://axleaddict.com/auto-repair/A...g-System-Tests[/QUOTE

Thanks, I will take a look at link when I have a chance.