legacycentral bbs

the alternator on most subarus have a 2 wire clip and some have a 3 wire clip. what are these for? also the post to which 2 large wires are bolted to? what do these do.

my understandnig of the system is that the post is what sends teh charge back to the battery. i had my alternators tested and they are fine but the system still wont charge. there is something inherently wrong with the system but we hardwired the alternator to teh battery with a 6 gauge wire and a 65 amp inline fuse and it still wont charge the system. what could be causing this???

On our alternators, there are three wires, and the post.

You are correct in that the post that connects to the battery sends the charge to it.

Out of the three wires, one is called the sense, the other is called the light, and the third is the turn on signal, which is tied into the igntion.

The turn on signal just tells the alternator, ok I'm good to make electricity now. On the newer models, they use an RPM sensitive turn on switch.

I don't claim to know exactly how everything works, but I believe the sense input basically detects voltage of the system, which then goes to the internal regulator of the alternator, and adjusts how much voltage is being sent out.

The light input goes to the alternator dash light I believe and/or is used for diagnostic purposes.

Here's some scans from the FSM, which may or may not be helpful.

http://www.main.experiencetherave.com:8 ... nator1.jpg
http://www.main.experiencetherave.com:8 ... nator2.jpg

ok thanks josh that was pretty helpful, would it make sence than if i was using the newer alternator with only the two wires that if my tach isnt working than my alternator wont turn on either???

The tach doesn't have anything to do with the alternator. If the newer alternator is wired correctly, everything should work. I'm running a newer style alternator, and I just taped up that 3rd ignition lead wire.

Has the alternator ever seemed to work correctly? Or did something just happen?

i had the alternator tested and its fine. at least the impreza one is. i didnt have the legacy one thats on the car now tested but it was fine when removed. this i on my swap and so far as i can tell the remaining things wrong are a power draw while the car is off, the alternator somehow not getting power back to the battery even when hardwired, and the temp and fuel level gauge and tach not working. so im trying to attack one at a time. also i dont have my blower motor in or my ac in either. i noticed that i had a lot of things that wouldnt work when the dash soround was missing so could some of my problems be caused by the blower and ac boxes being out of teh car?

Can you elaborate on what all was done with your "swap" and what has changed.

92 legacy motor into a 95 impreza chassis. turbo motor engine harness spliced into 95 chassis harness.


orignaly using the 95 alternator now on 92 alternator with same effects.

not present now/atm are cruise control, airbag system, blower motor and ac box and compressor.

btw this is all i know. matt monson did the wiring not me. my understanding of wiring is minimal.

Hmmm.....This is a very tangled web....without wiring diagrams of both cars and a fair amount of time to look over everything, I'm limited as to what I can do....

checked for a fuse today, there is no such thing.