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#Alternator - 3 pin to 2 pin

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 Post subject: Alternator - 3 pin to 2 pin
PostPosted: Fri Sep 17, 2004 8:38 am 
First Gear
Joined: Thu Jan 08, 2004 4:37 pm
Posts: 128
I think I found a thread where vrg3 dealt with this but I want to make sure:

When you install a later Sube 2-wire alternator, you connect the two pin black/white to the old harness black/white, the other pin to the old harness thick-guage white, and the car's yellow wire you leave unattached to the 2-wire alternator?

I was looking at the wiring diagram and I think you might be able to short the yellow to the black/white wire instead....

A

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www.musketeerracing.com
1991 Legacy SS 5MT Rally car (sold)
1993 Legacy SS 5MT Street car (selling)
1997 Lancer Evo IV RS Rally car (sold)
2006 Lancer Evo IX RS Rally car
2009 Lancer Evo X RS Rally car
1989 240SX SR20 Drift car


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 Post subject:
PostPosted: Fri Sep 17, 2004 2:43 pm 
Vikash
Joined: Sun Nov 03, 2002 2:13 am
Posts: 13020
Location: USA, OH, Cleveland (sometimes visiting DC though)
What year alternator are you trying to install on your car?

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"Just reading vrg3's convoluted, information-packed posts made me feel better all over again." -- subyluvr2212


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PostPosted: Fri Sep 17, 2004 3:04 pm 
Site Admin
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Joined: Tue Oct 15, 2002 11:37 am
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Location: Houston, Tx
I installed a newer HO one on my car. The third wire is a turn on lead. The older alternators used a signal from the ECU to tell the alternator that it could "turn on"

The newer ones are rpm based. So they automatically turn on, once rpms are above a certain point.

So you can pretty much just tuck that third turn on lead away in the harness

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Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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 Post subject:
PostPosted: Fri Sep 17, 2004 3:34 pm 
First Gear
Joined: Thu Jan 08, 2004 4:37 pm
Posts: 128
I saw this info in the thread about your HO alternator, Legacy777. But i just wanted to make sure about the "leave it disconnected" advice. Looking at the wiring diagram, the "turn on lead" is fused at 15A to the ignition switch, hits the coil, and a diode. I have no idea what it does, but then I really don't know how alternators work...

Can you guys confirm the rest of my post? black/white to black/white, and thick white to small-guage purple (I think).

Don't know what year alt I installed - Lachute just gave me a parts one.

Here's the story: last night I was driving back from the dragstrip with the director of the show we were filming there (I'm hosting!) and suddenly the headlights got very bright and then went back to normal and all the idiot lights were on. Looked like signature alternator failure to me.

So I limped to the place we were meeting the producer for dinner, did the dinner, and then said I had something to do and bagged the rest of the evening.

Fortunately I had the spare alternator in the trunk (I'm like 600 miles from home and it's 11pm). I installed it and based on the manual guessed at the wiring. It works when wired the way I describe above. I just don't know if it will continue to work that way.

A.

_________________
ACP
www.musketeerracing.com
1991 Legacy SS 5MT Rally car (sold)
1993 Legacy SS 5MT Street car (selling)
1997 Lancer Evo IV RS Rally car (sold)
2006 Lancer Evo IX RS Rally car
2009 Lancer Evo X RS Rally car
1989 240SX SR20 Drift car


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PostPosted: Fri Sep 17, 2004 5:28 pm 
Site Admin
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Posts: 25180
Location: Houston, Tx
I've had mine disconnected for almost a year now.....have had zero electrical issues.

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Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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 Post subject:
PostPosted: Sun Sep 19, 2004 5:33 pm 
Vikash
Joined: Sun Nov 03, 2002 2:13 am
Posts: 13020
Location: USA, OH, Cleveland (sometimes visiting DC though)
I think Josh is right.

If I have this right, our stock alternator harness connectors have these three wires:

The white "sense" line connects to the output of the alternator, so the voltage regulator can read how much voltage the alternator is putting out.

The yellow "ignition" line connects to the ignition switch, so turning on the ignition activates the field coils.

The black-with-white-stripe "light" line connects to the charge warning light on the dash.

Josh's alternator was self-exciting, so it didn't need the "ignition" line. I guess later Subaru ones are self-exciting too?

Does the charge warning light turn on when you turn the ignition on without starting the engine? If it does, and if the system is charging, then you should be fine tucking the ignition wire away (make sure it can't short to anything though!) and leaving it.

As an extra check you might try removing the drivebelt and then starting the engine to make sure the warning light comes on.

And you might want to make sure that there isn't power being drained from the battery when parked by measuring the current through the negative battery terminal with the ignition off. It shouldn't be more than a couple dozen milliamps.

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"Just reading vrg3's convoluted, information-packed posts made me feel better all over again." -- subyluvr2212


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