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Alternator wiring question


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22 replies to this topic

#1 trikerbob

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Posted 02 January 2007 - 07:24 PM

Hi guys, Need some help wiring my Alt that I have on my EA82 1.8 Carbed motor that I have in my Trike. Since I don't have the normal wiring harness I don't know where things go.

On the back of the Alt there is 1 connection that says Battery on it. Thats a no brainier. The other connection is recessed in the body of the alt and has 2 blade type connectors. Does any one know where these two connections will go. I know in some cases there might have been an external regulater to connect to, but I don't know if this Alt requires a regulater or if its got the internal regulater like so many now have.

A little help would be appreciated.

Thanks. Bob

#2 mellow65

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Posted 02 January 2007 - 07:34 PM

i know this doesn't completely answer your question. on the two prong plug, one needs keyed power and the other is for the idiot light on the dash. now the sad thing is i don't know which one is which because i haven't gotten that far in doing my alternator yet.

some one will chime in with the correct answer here soon

#3 trikerbob

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Posted 02 January 2007 - 11:30 PM

Thanks for the response, based on that answer I think I know what to do, but I do hope to get a few more answers just to be sure about it. If one goes to the switch and the other to the light on the dash, then it probably won't matter what one goes where. I'm used to the VW single wire alt that has to have power through a light to tickle the alt to make it charge. However, the VW atls only have 1 connecter besides the battery one to go through the light, so this throws me a little. So I'll hope for a couple other answers before I start hooking up wires.

Bob

QUOTE=mellow65]i know this doesn't completely answer your question. on the two prong plug, one needs keyed power and the other is for the idiot light on the dash. now the sad thing is i don't know which one is which because i haven't gotten that far in doing my alternator yet.

some one will chime in with the correct answer here soon[/QUOTE]

#4 GeneralDisorder

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Posted 02 January 2007 - 11:47 PM

Ok - Alternator 101.

The subaru EA series alternator uses the normal GM remote sensing system of the GM 2 wire and 3 wire alternators of the past. (Note - 1 wire alternators are an aftermarket thing - haven't been used on any production vehicle that I know of, and frankly shouldn't be either. Totally stupid idea made for people that don't understand electricity).

The LARGE ring terminal mount on the back of the alt goes to the "main junction". As does the smaller black/white wire from the 2 pin connector. The large wire is the main alternator supply - it charges the battery, and handles current demands of the electrical sysem. The smaller wire is the "sensor". The alternator uses this wire to regulate voltage AT the main junction. With accesories turned on, the voltage at the junction should remain a constant 14.5 volts. The output at the back of the alt will be higher to maintain the proper voltage at the junction. ALL your main electrical circuits should eminate from the main junction so each circuit has the correct 14.5 volts.

The third and final wire (smallest of the three) should run through a 15 amp fuse to a single 12v lamp on the dash. This will illuminate if the votage drops or the regulator malfunctions. It's known as the "charge indicator" lamp.

With very minimal modifications you can use a GM 2 or 3 wire alternator. I had one on my EA81 wagon for a bit. Or there's the nissan maxima 90 amp that is basically a bolt it. They all operate the same wireing wise.

GD

#5 trikerbob

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Posted 03 January 2007 - 11:01 AM

Thanks General, I still need just a little more info here. I don't have any part of the wiring harness for the motor or Alt. I don't have any way of telling what one of those two blade connecters would be for the light and what one would connect at the main junction with the Batt wire.

If you could pull your plug and tell me what one would be the black/while wire I can go from there. As you know one blade is - the other l.

Thanks again for your help.

Bob

Ok - Alternator 101.

The subaru EA series alternator uses the normal GM remote sensing system of the GM 2 wire and 3 wire alternators of the past. (Note - 1 wire alternators are an aftermarket thing - haven't been used on any production vehicle that I know of, and frankly shouldn't be either. Totally stupid idea made for people that don't understand electricity).

The LARGE ring terminal mount on the back of the alt goes to the "main junction". As does the smaller black/white wire from the 2 pin connector. The large wire is the main alternator supply - it charges the battery, and handles current demands of the electrical sysem. The smaller wire is the "sensor". The alternator uses this wire to regulate voltage AT the main junction. With accesories turned on, the voltage at the junction should remain a constant 14.5 volts. The output at the back of the alt will be higher to maintain the proper voltage at the junction. ALL your main electrical circuits should eminate from the main junction so each circuit has the correct 14.5 volts.

The third and final wire (smallest of the three) should run through a 15 amp fuse to a single 12v lamp on the dash. This will illuminate if the votage drops or the regulator malfunctions. It's known as the "charge indicator" lamp.

With very minimal modifications you can use a GM 2 or 3 wire alternator. I had one on my EA81 wagon for a bit. Or there's the nissan maxima 90 amp that is basically a bolt it. They all operate the same wireing wise.

GD



#6 RavenTBK

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Posted 03 January 2007 - 01:19 PM

Thanks General, I still need just a little more info here. I don't have any part of the wiring harness for the motor or Alt. I don't have any way of telling what one of those two blade connecters would be for the light and what one would connect at the main junction with the Batt wire.

If you could pull your plug and tell me what one would be the black/while wire I can go from there. As you know one blade is - the other l.

Thanks again for your help.

Bob

To answer your question, on the T plug, the top of the T is the field sense wire, and the bottom of the T is the idiot light.

Check my post in the USRM if you want to see for yourself.. theres pics from (link) my alt swap that'd help you.

#7 trikerbob

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Posted 03 January 2007 - 03:11 PM

Thanks, thats what I needed to know, I would have guessed that was the way they went but I don't like to guess with electrical items.

Bob:)

To answer your question, on the T plug, the top of the T is the field sense wire, and the bottom of the T is the idiot light.

Check my post in the USRM if you want to see for yourself.. theres pics from (link) my alt swap that'd help you.



#8 trikerbob

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Posted 03 January 2007 - 05:35 PM

Ok, if I understand this right, the top of the T wire will go to the switch and the bottom of the T will go to the light.
Sounds reasonable to me.

thank you bob


To answer your question, on the T plug, the top of the T is the field sense wire, and the bottom of the T is the idiot light.

Check my post in the USRM if you want to see for yourself.. theres pics from (link) my alt swap that'd help you.



#9 GeneralDisorder

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Posted 03 January 2007 - 06:17 PM

Ok, if I understand this right, the top of the T wire will go to the switch and the bottom of the T will go to the light.
Sounds reasonable to me.

thank you bob


No switch - it goes to the main junction - where your fuseible links are located if you are using them (you should be).

GD

#10 trikerbob

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Posted 03 January 2007 - 08:11 PM

Well I'm confuses now. I did try it the way I stated in the earlier post and got nothing.

Ok, this is how I am hooked up. The terminal marked battery I have going to the main battery terminal on my starter soleniod. Its getting constant direct power from the battery. This does not go through any switch. Now if I was to connect the other wire to this same post on the soleniod, it too would have constant direct power from the battery. Is this what your telling me I need to do? then the bottom of the T terminal on the Alt would go to the light. I assume the light then would be grounded.

If that is correct I have to wonder if this wouldn't be a drain on the battery even when its not running.

I have always thought the light should come on when the key is turned on then go off as soon as the motor started. Thats why I assumed one of those T terminals would go through the switch. ???

I am electrical challenged to a larg extent with this kind of stuff so be as spicific as possible so I can follow you.

Also I was trying to get this info from the book and noticed they refer to a voltage regulater. Externial for early models, internial for late models. I assume my 85 would be considered early. I don't have a regulater. I assumed the Alt had an internal reg in it..Yea, or Nay. Perhaps part of my problem is no regulater?

Bob:confused:

No switch - it goes to the main junction - where your fuseible links are located if you are using them (you should be).

GD



#11 GeneralDisorder

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Posted 03 January 2007 - 08:28 PM

Ok - for safety reasons, and simply so you aren't pulling your hair out trying to figure this out, you REALLY need to understand how this works. I don't have the time to make up schematics and such, but here's some links that will clear everything up for you. Read this stuff, and you'll understand how to setup your electrical circuits.

http://www.rowand.ne...ratorTheory.htm

http://www.madelectr...threewire.shtml

And yes, all alternators after 81 were internal regulated.

GD

#12 RavenTBK

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Posted 03 January 2007 - 08:57 PM

I'm on a slow connection, so I wont read the links that GD posted, although I am sure they contain a wealth of knowledge... that doesnt mean YOU shouldnt read them, just that I wont. ;) GD knows his schitt... and if he says to read something, I'd suggest you do it.

Here's how it goes in its original setup, and not necessarily how you should hook it up on your trike....

I understand not being electrically savvy, we all were at one point.. so I'll break it down barney style. :D Again, this is how its set up in a normal configuration...

The "field sense" wire I referred to earlier is just a switched 12v source. It is switched with the ignition.. providing +12v with ignition on, and 0v when the ignition is off. Its the wire that tells the alternator to "power up" its internal magnets and make power. With the ignition off, no power is supplied to this wire, which "shuts off" the internals in the alternator and it produces (and draws) no power.

The idiot light wire just goes straight into the hot side of the idiot bulb in the dash.

NOW back to reality here.. how GD was suggesting (in his last post) was to connect your field sense wire directly to unswitched +12v at the main junction. There is NO PROBLEM with doing it this way. The only downside is the alternator will remain energized with the motor off, and if stored for a long time, you could possibly run your battery down. Emphasis on long time, and possibly.

As an easier alternative to the above, you could easily turn the field sense wire into a jumper, that twists around the back of the alternator and connects to the output stud, creating the same effect. This essentially creates a "one wire" alternator.. one wire meaning the only wire that leaves it is the one that runs from the output stud directly to the battery or main junction (preferably through a breaker for safety sake).

So yeah, your options are these:
a) run the field sense wire through an on/off switch (ignition), to turn on/off the alternator along with the engine
B) jump the field sense wire back to +12v, and call it a day.

Use your building plans to decide whether you want to include the idiot light.

Cheers.

#13 GeneralDisorder

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Posted 03 January 2007 - 09:25 PM

There should be no switch for the remote sensor wire. Here's the diagram for it (stole from one of the above links):

Posted Image

The dash light is the one that needs switched ignition power. Then the alternator will provide the ground when it's field isn't energized to light the lamp. When the alt is working properly it provides full field current to the bulb, and thus the ignition switched voltage and the field curent from the alt cancel each other out.

Again, there should be NO switches involved in the two wires to the main junction. They should be connected directly to battery positive through fusible links. (ideally no wire should leave the junction without a fusible link). This is by design and will not drain your battery. It's also how it's hooked up in the car originally.

GD

#14 RavenTBK

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Posted 03 January 2007 - 11:24 PM

I stand corrected in the original hookup. :dead:

I learned what I know about the Subaru setup from testing on my Brat during the GM swap. When I first got the Brat, it sure wasnt stock, so it wouldnt surprise me if things were re-done before I got it. In my particular case, the field sense wire was switched by the ignition, and the idiot light ran from the terminal directly to the hot side of the dash lamp, therefore I assumed that terminal "linked" with the B+ stud upon failure, providing +12v to the lamp. I again rump roastumed that was the stock configuration. So thats how I left it when the GM went in.

I re-learn about assumptions each and every day, yet for some reason it never sticks. :rolleyes:

Like I said, GD knows his crap. Personally, I enjoy failure, and setting things on fire... thats how I learn. ;) Bob, ignore me. I'm a much better thief than mechanic.

#15 trikerbob

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Posted 04 January 2007 - 09:42 AM

Thay you so much for being patiant with me on this matter. I did read the stuff in the links, most of it anyway and I think I'm beginning to get the picture now. I'm taking my Trike to the Muffler shop this morning to get pipes fitted so I won't be able to try the wiring for a coule days. I took my Alt to a shop and had it gone through, new brushes and such. Came back looking like new and I assume when they do that they also test them to know they work properly. So I expect it to charge properly once I get it wired right. I'll let you know when I get it back and try again.

Thanks, Bob

There should be no switch for the remote sensor wire. Here's the diagram for it (stole from one of the above links):

Posted Image

The dash light is the one that needs switched ignition power. Then the alternator will provide the ground when it's field isn't energized to light the lamp. When the alt is working properly it provides full field current to the bulb, and thus the ignition switched voltage and the field curent from the alt cancel each other out.

Again, there should be NO switches involved in the two wires to the main junction. They should be connected directly to battery positive through fusible links. (ideally no wire should leave the junction without a fusible link). This is by design and will not drain your battery. It's also how it's hooked up in the car originally.

GD



#16 trikerbob

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Posted 04 January 2007 - 09:43 AM

Thanks Ravin,

With you and Generls help I think I know what wires to stick where now. I'll know for sure in a couple days.

Bob

I stand corrected in the original hookup. :dead:

I learned what I know about the Subaru setup from testing on my Brat during the GM swap. When I first got the Brat, it sure wasnt stock, so it wouldnt surprise me if things were re-done before I got it. In my particular case, the field sense wire was switched by the ignition, and the idiot light ran from the terminal directly to the hot side of the dash lamp, therefore I assumed that terminal "linked" with the B+ stud upon failure, providing +12v to the lamp. I again rump roastumed that was the stock configuration. So thats how I left it when the GM went in.

I re-learn about assumptions each and every day, yet for some reason it never sticks. :rolleyes:

Like I said, GD knows his crap. Personally, I enjoy failure, and setting things on fire... thats how I learn. ;) Bob, ignore me. I'm a much better thief than mechanic.



#17 trikerbob

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Posted 04 January 2007 - 09:50 AM

Posted Image

This is the photo I picked out that seems to be the one for my setup. I don't understand about the resister though.

Bob



Ok - for safety reasons, and simply so you aren't pulling your hair out trying to figure this out, you REALLY need to understand how this works. I don't have the time to make up schematics and such, but here's some links that will clear everything up for you. Read this stuff, and you'll understand how to setup your electrical circuits.

http://www.rowand.ne...ratorTheory.htm

http://www.madelectr...threewire.shtml

And yes, all alternators after 81 were internal regulated.

GD



#18 GeneralDisorder

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Posted 04 January 2007 - 02:54 PM

Here's quote from that page:

"The dashboard indicator light circuit also typically has an extra wire with a calibrated resistance in it. This wire is run in parallel to the indicator light and has about a 10ohm resistance. It's purpose is to allow slightly more current to flow to the alternator field current system at initial start-up to make sure the alternator begins producing power as soon as the engine starts. About 1 amp total current is flowing to the field current between the light and the resistance wire, with the resistance wire supplying about 3/4 of an amp. This extra resistance wire does not affect the functionality of the indicator light in any way.

NOTE: I've been informed by my readers that a Radio Shack 10 ohm 10 watt 10% wire wound ceramic resistor (part #271-132) has worked well on their GM vehicles. Use caution if you decide to do custom wiring work with resistors as they can get hot and melt stuff."

Now I'm not sure what the resistor value is on the subaru's.... probably similar but I've never tested it. It's probably part of the lamp assembly/voltmeter in the guage cluster, or the lamp itself has a low enough resistance. Probably be a good idea to just go with the GM reccomendation.



GD

#19 trikerbob

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Posted 04 January 2007 - 03:35 PM

Ok thanks again General, I'll post my results as soon as I'm able to try it.

bob

Here's quote from that page:

"The dashboard indicator light circuit also typically has an extra wire with a calibrated resistance in it. This wire is run in parallel to the indicator light and has about a 10ohm resistance. It's purpose is to allow slightly more current to flow to the alternator field current system at initial start-up to make sure the alternator begins producing power as soon as the engine starts. About 1 amp total current is flowing to the field current between the light and the resistance wire, with the resistance wire supplying about 3/4 of an amp. This extra resistance wire does not affect the functionality of the indicator light in any way.

NOTE: I've been informed by my readers that a Radio Shack 10 ohm 10 watt 10% wire wound ceramic resistor (part #271-132) has worked well on their GM vehicles. Use caution if you decide to do custom wiring work with resistors as they can get hot and melt stuff."

Now I'm not sure what the resistor value is on the subaru's.... probably similar but I've never tested it. It's probably part of the lamp assembly/voltmeter in the guage cluster, or the lamp itself has a low enough resistance. Probably be a good idea to just go with the GM reccomendation.



GD



#20 TomRhere

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Posted 05 January 2007 - 04:13 AM

The resistor in the "light circuit" will also allow the alt to "charge" if the bulb should burn-out or otherwise blow. So I would suggest putting one in.

#21 GeneralDisorder

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Posted 05 January 2007 - 04:30 AM

The resistor in the "light circuit" will also allow the alt to "charge" if the bulb should burn-out or otherwise blow. So I would suggest putting one in.


Excelent point - otherwise you will have to rev the engine to around 3,500 RPM for the regulator to self excite. That's how the alt is in my wagon right now cause I neglected to hook up the bulb/resistor when I converted from digi-dash to analog.

GD

#22 trikerbob

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Posted 05 January 2007 - 03:36 PM

Thanks a lot you guys for all your help. After trying and trying, I finally took what was suspose to be a freshly rebuilt Alt, to the parts house and had them test it. It was no good so I got a new one and hooked it up and its putting out 14.5 just like it should. The new came with a resister right on the Alt. So I'm in business now. Just need a water temp gage now and I'm complete. Got my pipes built yesterday and drove it home. Sounds like a big block V8 now. Actually its louder than I had wanted it to be but its not too bad. It does have a real nice deep mellow rumble to it. I start my regestration process next week then I'll be looking for some brakes in the weather so I can get it up in the foot hills for a goos test.

You guys have been a big help, Thanks

BobPosted Image

Excelent point - otherwise you will have to rev the engine to around 3,500 RPM for the regulator to self excite. That's how the alt is in my wagon right now cause I neglected to hook up the bulb/resistor when I converted from digi-dash to analog.

GD



#23 RavenTBK

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Posted 06 January 2007 - 01:33 AM

Posted Image


Effin schweet... :slobber:




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