Alternator OEM FORD or Bosch

You can get a Bosch alternator for a KA and swap the pulleys

Any time I see overvoltage faults I replace the alternator. Check the charging voltage and confirm that it's charging higher than 15.0v (it may happen only briefly under some conditions). If it is then unplug the connector from the alternator. That should default it to 14.3v. If it still overcharges then you've confirmed a faulty alternator.

Lucky for us, the Alternator was in fact faulty (it was a Bosch btw) and that the previous owner replaced it a few months prior, meaning it was still under warranty.

Bosch is a great aftermarket option.

Yes, if it was from an OEM supplier to Lexus or the auto industry, such as Denso (1/3 owned by Toyota/Lexus), AC Delco, or Bosch, but I would not buy a mystery brand, especially not a rebuilt, because I don't know how much they get rebuilt or tested.

Changed it for another OEM Bosch new (not reman). Subsequent test showed it was now good.

I wasn't crazy with the AC Delco (GM) alternator conversion when I used it on my MGB engine. The Bosch ones seemed to be a little better designed and easier to convert, plus they looked simmilar to the Lucas ones.

Bosch rebuilt alternators are like $175 online. Lots of people experienced low quality rebuilts. Have people had good luck with Bosch rebuilts?

Go with a new OEM. I had a Ford E250 I put a remanufactured one in and it lasted like 2000 miles and gave out.

ended up going with a Bosch remanufactured alternator. Installed it today, went super smooth, charged up the battery as I was installing it, got everything buttoned up and started it up. Battery light still on, voltage is at around 11.9 and dropping. Will randomly jump up to 14.4 volts, no correlation with revving the engine or putting a load on the electrical system.