Alternator Failure Modes?

[TeCKis300]

2009 LX570 with 169k miles. 20-40A of aftermarket loads on occasion. Swapped out this failing alternator that showed symptoms of low voltage and not sufficiently charging the starting battery.

RTH: Alternator Suspect Voltage Output

forum.ih8mud.com

Tore this down expecting the brushes to be worn. Surprised, there was still plenty of meat left in the brushes. Commutator looked great. Bearings felt solid with no play and buttery smooth. Belt is fine. Probably the regulator side of things?

I'm not an alternator expert by any means and didn't dig further. Anyone have any insight into the failure mode?

On my Porsche alternator which is very similar to other German makes, it was easy enough to change the regulator that failed. Is that a component that can be changed on Yota alternators?

 

[bjowett]

The regulator can be swapped. It’s the brown part that the harness plugs into.

 

[Sandroad]

On my 80, it wasn’t the alternator that failed, it was a corroded connector that simulated a failure. Cleaning up and greasing the connector solved the problem with output. Any chance that’s the failure mode on your LX?

 

[TeCKis300]

The regulator can be swapped. It’s the brown part that the harness plugs into.

Perfect. Doesn't look too hard to unbolt that part. Unfortunately, the part number isn't identified in the exploded diagrams? In reality, with the time and effort it took to get out the alternator, I just as soon replace the whole unit than risk a bad diagnosis to save money.

On my 80, it wasn’t the alternator that failed, it was a corroded connector that simulated a failure. Cleaning up and greasing the connector solved the problem with output. Any chance that’s the failure mode on your LX?

Always possible. I'm in the arid southwest so corrosion is rarely a problem. All the connections looked good as far as I could tell.