Hello,

I need some help because I seriously can't fathom where this problem could be. Context: 2008 Lexus IS250, RWD, Auto Trans, Non - ML audio, Non - Nav, 180,000 miles.

This problem started with the battery just being drained to the point where it wouldn't start. It became more and more frequent. When accelerating you could hear the RPM's coming through the speakers. Replaced the battery. Same problem. Tested the alternator - came back as only producing around 13v with the car running. Battery alone was around 12.4-12.7. Told my son he likely needed to replace his alternator soon.

Son was driving - Car audio went crazy. Loud distortion noise coming from the speakers at all. Factory radio had fade and balance to 10 and unable to change anything. Now the car works but with no audio (obviously).

Decided to replace the alternator from one from Advanced Autoparts to see if maybe it wasn't sending enough volts to the factory amp. Also changed serpentine belt. Figured it probably had to be done anyways. No change with factory audio - still broken. Removed factory amp to stop the noise. Car seemed to be behaving as normal. This was alternator #2.

The next day son was driving car. All lights lit up on dash. Lost power steering. Limped the car home. Battery was putting out proper volts when charged. Fusable link was good. Car started fine off the battery, but New Alternator was not putting out anything. All other fuses were good. Took the new alternator out. Brought it to advance auto parts. They bench tested it. It didn't work. They gave me Alternator #3.

Replaced with Alternator #3. Went to fire the car up... Nothing. Nothing at all. Checked fusable link. Alternator fuse was blown on Fusable link. Could bypass fusable link to start car fine. Alternator #3 tested normal like this, but I didn't want to run it like this (with blown fusable link) for longer than a few seconds.

Replaced Fusable link.

Car runs and starts fine. Everything is running like it should. Alternator #3 and battery are putting out the proper voltage. (Did not drive the car here). Son decides to put the factory amp in to see if that works now that the alternator is putting out the proper voltage. Plugs the factory amp connectors in, bolts it down. Goes to start the car. Car cranks for half a second and then everything goes dark. There is no power to the car. The start button doesn't do anything.

I hook a trickle charger to the battery and then the power comes back to the car. Son hits start. Car fires up. I test the alternator. It is putting out less voltage than before. Son pulls factory amp. Car starts fine. Alternator #3 tests back in the normal range for voltage without the factory amp. I figure there is a short in the amp and that is what has been causing his battery drain. I thought that we, finally, identified the problem.

Drove the car for about an hour. Everything works great. However, there was a smell coming from where the new fusable link, or below is. It wasn't overpowering. It wasn't like melted plastic, but I guess the best way to describe it was warm plastic. Probably should have done some diagnostics here, but thought maybe it was just the new alternator or the new fusible link "breaking in" since car was driving fine and no fuses had popped.

The next day son drove the car to school. Battery light started flashing. Told him to come back. Popped the hood. Same "warm plastic smell" coming from the location of the new Fusable link. A little stronger this time, but still not as bad as a fire or melted plastic. Checked the voltage - Alternator #3 is no longer putting out any voltage. Fusable link is good.

At this point - I am at a complete loss at what could be causing this problem. I could install Alternator #4, but I am worried that one is just going to fry. Any ideas?????

 

If I was a betting person, bad alternator, reversed polarity, blown fuses, and alternator does not like reverse polarity either, followed by unstable input to the ECM, from blow fuseable link...

It's a tough story and I doubt any aftermarket amp can handle a reverse polarity encounter like the OEM.. JM2C but if this car had an aftermarket amp that is poorly installed, has taken a hit from polarity reversal, Id toss it until a new proper install can be be done...

Take away:
Good batteries last about 4 years in moderate climates. Cheap, way less. Don't leave a bad battery in too long or it will kill it!
Nothing but Denso remanufactured alternators work in these cars. Cheap alternators seem to have sketchy feedback or regulation of voltage and just don't work well.

Rockauto.com is a good source for reman alternators. I'd start there and have the lad suffer in silence without tunes...

JM2C