My niece has a 2001 IS 300 which has been having issues with the battery/alternator. I went to the car yesterday and it was DEAD. So I pulled the battery, took it to AutoZone, they charged it and said the battery is good. So I clean the battery post and the cable connectors, install the battery and fire it up. I have a www.ScanGauge.com
(an OBD2 tool) so I plug that in and watch the volts.
When started the volts read 14.1. I take the car for a drive and the first stop or 2 the volts drop to 13.6 - 13.8, no big deal. About a mile away, 3 minutes into the drive, I stop at a light and the volts drop to 12.3 - 12.4. I drive a few miles and at stops the volts drop as low as 11.7. I figure the alternator is dropping off line and at low idles, I may just be reading battery voltage. It goes a little higher when I turn off the AC and head lights.
So I figure the alternator has an issue. I tell my brother and suggest a Toyota or Lexus part, he calls his son that works at a Lexus dealer, they call me back and tell me to go to a local auto parts store and get a new alternator for $125 with a lifetime warranty. I don't put up a fight and go forward and install the store box alternator.
I crank the car, 14.4 volts, I drive the car and a mile down the road I stop at a traffic light and the darn volts drop to 12.2 - 12.4. Another mile down the road and it drops to 11.9 volts. While driving it is between 13.8 - 14.2 volts.
Did I get a bad alternator from the store or does this car have another issue?