Keep blowing Alternator

[roehlerichgmail.com]

I am new to this forum. I have a 01 Legacy automatic. I am on my 4th alternator and second battery in 2 weeks.

Here is what started it all: 2 wires on positive side on battery were loose under the wing nut. Car stopped running. I tightened the wing nut started the car and drove ok with battery light on for about 30 min. Then battery light went off. Next day alternator stopped charging battery was dead without any warning lights while driving. New alternator would initially charge fine at idle but then got hot started smelling and stopped charging again without any warning. Shop then installed new alternator and battery. Took 4 days and car died again. Alternator will put out 12.4 volts only above 1500 rpm. So that one is about dead too.

Question: what does the 2 prong connector go to on the top of the alternator? Do I need a new computer? I don’t know what talks to the alternator but it is not working. My shop is clueless. Please help. Thanks.

[doublechaz]

I had many bad alternators from Autozone. No problem when I switched to a Napa. Seems like Autozone gets their rebuilts from chimps tripping on acid.

 

It's nearly certainly not the ECU. Mostly the ECU failing makes the car not run at all.

 

You should be looking for faults in the big wires between alternator, battery, starter, and engine bay fuse block. Probably corrosion/high resistance.

[RumbleRumble]

Are all the grounds connected? also pic of said two prong connector.

[roehlerichgmail.com]

I measured all the resistance I can think of. Even looked for ground to alternator and only got the 0.2V creep which is OK. I did order a new connector. I can see battery voltage on middle pin. 1st pin should go to battery indicator in dash but that does not light up anymore when battery is going LOW. So something inside the alternator is not switching properly. Alternator heats up like crazy and eventually starts to smell/burn. First it will only charge at higher RPMs and then it completely fails. this is my 4th one.

So the alternator is not getting proper signal from somewhere. Where do those 2 wires from the green alternator connector lead back to? Should I just install a new ground from alternator case to battery? Car is at the shop now. I am waiting for the new connector...

[roehlerichgmail.com]

I also checked the fuse #3 for battery indicator light and it is good.

[doublechaz]

This battery light comes on when you first key on before starting? With stuff that crazy it could have burned out the indicator lamp. I expect the lamp would go before the fuse would, fuses are for protecting the wires from an electrical fire not for protecting components in the circuit.

 

What year car is this?

 

I thought voltage regulation was done in the alternator on our cars, but I could be wrong.

[RumbleRumble]

you can take it out and have it benched tested at local parts store

[ehsnils]

On the '04 there are 2 fuses for the alternator, the main fuse and a 7.5A fuse.

 

 

Not sure if the '01 has the same wiring, but check the fuses in the fuse box anyway since this can be for voltage feedback to the alternator. And if it gets incorrect voltage feedback then it could behave badly.