Alternator Connections

Threshld1 · Post by **Threshld1** » Sun Apr 09, 2006 3:19 am

Hey im looking to swap out my alternator for a newer style connector wrx alternator. Im looking for the wire codes for the 3 wires on the old connector so i know which to connect to L (light) S (stator) C (constant battery+) i believe

Threshld1 · Post by **Threshld1** » Sun Apr 09, 2006 4:51 am

found a diagram on the old connector S, IG, L so would i be correct that S and L are the same and IG is C or the switched B+ signal?

it also appears that the stator wire on my legacy is much bigger than the newer style. does anyone know how much current that wire carries and if it needs to be as large of a gauge for the new alternator?

vrg3 · Post by **vrg3** » Mon Apr 10, 2006 3:45 pm

S stands for Sense. The Sense terminal is connected to the battery so that the voltage regulator can sense battery voltage. The stock Sense wire is white.

The stock Light wire is black with a white stripe.

The stock Ignition wire is yellow. The Ignition terminal is connected to ignition-switched power so that the voltage regulator only turns on when the car is running (or about to run).

The B terminal is the output terminal -- the M6x1.0 stud that the wire with the ring terminal goes to.

The WRX alternator apparently doesn't have an Ignition wire, so I guess it's self-exciting. The alternator has a 3-pin connector on it:

Code: Select all

 __| |__ 
| 3 2 1 |
|_______|

Pin 1 is Light.
Pin 2 is Sense.

I don't know what the C terminal is, but it shouldn't be connected to anything.

Threshld1 · Post by **Threshld1** » Mon Apr 10, 2006 10:57 pm

perfect thank you.
am i going to have any issues going from such a large wire (white ~12awg) on the sense to the connector with maybe 18awg?
should i just run a new line from the bat to the sense that is the same size to avoid any resistance differences?

vrg3 · Post by **vrg3** » Tue Apr 11, 2006 2:23 pm

The sense wire doesn't have to be very thick, because not much current flows through it, but why don't you just use the stock white wire?

Threshld1 · Post by **Threshld1** » Tue Apr 11, 2006 8:22 pm

oh that was my plan im just wondering if there is going to be any issue soldering that white wire to the much smaller size wire on the connector im using. If im going to experience any voltage drop on that size change or not. Im actually using a GM TPS sensor connector that conviently fits perfectly.

vrg3 · Post by **vrg3** » Tue Apr 11, 2006 8:46 pm

Oh, so you'd just have a couple centimeters of the thin GM TPS wire? That should be okay.

Threshld1 · Post by **Threshld1** » Tue Apr 11, 2006 8:49 pm

exactly, sounds good ill post pics when i get it in today. Thanks a ton for your help

vrg3 · Post by **vrg3** » Tue Apr 11, 2006 9:05 pm

No problem. I hope it works. Pics would be great for others trying to do the same job.

Threshld1 · Post by **Threshld1** » Wed Apr 12, 2006 2:46 pm

got her running no problems. reading a solid 14v at idle with accessories on. Bearings on my old alt were definatly shot. here are pictures

Pics

I just soldered the 2 connections and wraped them with some cut to length heat shrink wrap. Then just stuck a small peice of loombing on it.
The main battery post i had to drill out the ring terminals to fit the bigger stud. The lines reached just barely with my a/c compressor out, though i would like to extend it soon to remove any stress on that wire.
Alternator itself bolted right over no problems.

Hope this helps out anyone looking at doing this, let me know if you have any questions.

vrg3 · Post by **vrg3** » Wed Apr 12, 2006 2:59 pm

Great!

Do you by any chance have the part number for the GM TPS pigtail? Or did you just cut it off a junkyard car?

The WRX alternator uses a bigger stud? 8mm rather than 6mm?

That's a creative way to plumb the blowoff valve.

Threshld1 · Post by **Threshld1** » Wed Apr 12, 2006 3:44 pm

i wish i did. i just asked one of my friends whos going to school to be a tech when he was over looking at my friends STi with running issues. I just asked him out of the blue if he had any idea of where to get a connector. He runs to his car and comes back with that TPS connector, we had to cut off the lock clip as it was different but it doesnt come out. Next time i talk to him ill ask him if he knows a part # or what it came out of.

Yeah that bypass valve plumbing was a semi-quick, get it running, job. That green hose is silicon heater hose from napa, $15 a foor at regular price and i wasnt too happy to pay $5 a foot with discount either. I picked up some 90 deg elbows yesterday and i think im going to shorten up that line. Drop it down and under instead of around now that the coolant tank is mounted out of the way and not hanging.

vrg3 · Post by **vrg3** » Wed Apr 12, 2006 4:14 pm

Ohh... there's no locking tab holding the connector in? I guess it was too much to hope for that the General would make a connector that fits a Subaru completely right.

I'll comment on the bypass valve in your other thread.

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Alternator Connections

Alternator Connections