I have a 1993 LS400, over the past year or so I've had replace the alternator 3 times. The first time it died, I thought it was due to the fact that it had been due to the previously leak, now fixed, ps pump, so I replaced it, after this one died, I took it back to Napa, and got another 8 months later same situation, and then again months later. I'm on the 3rd one now and it doesn't seem to be charging my battery, everything else seems to work well on the car, all fuses are good, is there anything I can check or do other than replacing the alternator again? Also I changed the battery each time I changed the alternator because the batteries had died as well.

 

I get a nice chuckle when I see "searched" in subject headers, this invariably tells me not enough. I'm yanking your chain... We've had plenty and it boils down to several simple problems.

Barring wiring issues like shorts and a dead battery, that leaves the rebuilt alternator. Buy from another supplier, the ones you are getting are not quality units. This applies to many of those "lifetime" rebuilds sold at the mass auto parts stores. In my years using those parts, they all fail in warranty usually in 8 to 14 months. Costs time and labor that now I just buy from Carson Toyota. Not the least expensive though this reduces many-many headaches.

 

circuit breaker and/or fusible link issue.

provided it's not a voltage regulation issue ofc.

 

What's the voltage on the battery when the engine is on and when its off?

 

Ok well, I charged my battery, it seems to be working now, The battery has 12.5 volts off, and 15.2 on, despite dying before and not charging the battery. I looked at the belt and it is glazed, and starting to shred on the edge, so I'm wondering if this is what caused it. I put on a new belt, yet it rubs against the front of the left engine cover, the belt is installed correctly, is there some sort of spacer that should be there move to pulley farther "forward" or maybe I just need a new pulley? Any help is appreciated

 

It shouldn't be rubbing at all on anything. Check if there's any play or wobble on the pulleys. When the car is running does the belt move front to back, to indicate that the pulley is too far in for some reason? When you say "left side" do you mean the passenger side? If so it could have something to do with the alternator being put back on wrong. Or, for some weird reason, the alt could have the wrong pulley on it. If ya have that many problems with the NAPA alt, ya might want to get an OEM and be done with it.

 

Yeah sorry, passenger side. The alternator is in correctly and has the correct pulley for sure. The problem where its rubbing is on the power steering pump pulley. The belt seems to run normally, or rather as normally as possible for rubbing against the engine cover, but I'm going to double check that the pulley on the ps pump is ok tomorrow morning.

 

Could the tensioner be the problem? The pulley is on correctly and doesn't seem to have any play.

 

Many of the major car manufacturers have found that if the majority of your driving is done in stop and go traffic the alternator is not spun fast enough and long enough to recharge the battery. Some have gone so far as to change the diameter of the crank or alternator pulleys.

When you did your AMP draw test (I assume you have done some diagnosis) what were the readings? Have you checked for parasitic draw?

Try this simple test:
Set your volt meter to read AC volts, lowest range
Connect the black lead to the battery negative post
Connect the red to the positive battery post
Run the engine at 1500 RPM
Turn on all of the accessories
The reading should not exceed .09 volts (90mv) AC

If the readings are above .09 volts then the alternator is faulty (bad diodes)