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914World.com _ 914World Garage _ Subaru Swap - Alternator wiring

Posted by: jpnovak Jul 25 2011, 03:26 PM

Now that the engine is running I need to finalize some of the electrical connections. Notably, the alternator is near the top of the list.

Normally a regulated alternator has 5 connections

12V to battery
D+
D-
Df
GND

The Suby alternator is internally regulated so this elminates the Df wire.

I need to connect up the D+ and D- to complete the voltage comparator.

It looks like the blue D+ wire goes to Pin1 and I send 12V to Pin2 on the alternator. 12V becomes the effective D- wire to complete the circuit on Pin2. Basically, the current across the dash bulb that is a result of a difference in voltage between the alternator and the battery regulates the charge. At least, that is how I understand the wiring.

Any thoughts?

Posted by: BIGKAT_83 Jul 25 2011, 04:52 PM

From the subaru factory manual......
Attached Image

Bob

Posted by: jpnovak Jul 25 2011, 08:01 PM

Thanks Bob but that is a much newer alternator than the 97 that is in my car. I only have a battery post/terminal and a single 2-pin plug connector.

Posted by: kg6dxn Jul 25 2011, 08:39 PM

Not a Subie but... On my rotary conversion I ditched the Mazda Alt in favor of a Chevy 1 wire. I did use a 175 amp Power Master but you can get a 80 chevy at your FLAPS cheap. Makes the conversion easier than using the original parts.

Posted by: strawman Jul 26 2011, 12:04 AM

Here is a cut/paste from the 1998 Subaru Outback factory manual. Hope this helps...

Attached Image

Posted by: strawman Jul 26 2011, 12:43 AM

Just walked out in my garage and looked at my wiring harness from my 1994 Suby Legacy Turbo that I've adapted to my 914 harness. I matched the wires to the wiring diagram in my Chilton manual, and confirmed them in my electronic version of the factory manual.

My connections to the alternator are as follows:

1. Large gauge white wires on ring connector (to fusible link)

2. Round black plug with three wires:

a. White wire (to fusible link)
b. Yellow wire (to fuse #16)
c. Black/red wire (to charge indicator on dash).

What year and model did you engine come from?

Geoff

Posted by: jpnovak Jul 26 2011, 07:38 AM

Geoff,

Thank you for the listing. The engine is from a 1998 JDM GC8 Turbo (Forester). I can only find an Impreza wiring diagram. The connections are the same but the colors are very different.

I only have a 2-pin connector and a lug terminal on the alternator. I think your post confirms that I connect the dash light wire directly to the alternator and the other pin directly to the battery.

here is the Subaru Factory diagram I am working from.

IPB Image

The connection [ALT-1] goes directly to the dash charge indicator light. It would be same as the exciter current lamp on the 914 dash light.