AC Delco 'SI' Alternator wiring oddity, where is your 'excite' wire? - JeepForum.com
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Unread 08-01-2008, 02:07 PM   #1
Mike Romain
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AC Delco 'SI' Alternator wiring oddity, where is your 'excite' wire?

Folks, I have had a discussion with JeepHammer about the AC Delco alternator used in the later CJ's.

Basically over the last 15 years I have come across a lot of AC Delco 'SI' alternators with pin one and two on the white plug's connection reversed. Even on a Usenet auto tech group it has been noted as happening.

JeepHammer hasn't run across it.

I am up in Canada if that might make a difference.

In my case now, I am not sure which one I have in now, but my #1 with the solid core small wire or the excite is on the side of the white plug closest to the battery wire connection.

Where are your wires in the white plug?

I am curious as to how widespread this is.

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Unread 08-01-2008, 03:18 PM   #2
sparkey
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I have an 83 with the I-6 engine and the small wire is on the #1 terminal of the plug.Looking at the back of the alt. with the white plug on bottom it is on the right side, as you stated closest to the bat. terminal.
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Unread 08-01-2008, 03:28 PM   #3
Mike Romain
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Quote:
Originally Posted by sparkey View Post
I have an 83 with the I-6 engine and the small wire is on the #1 terminal of the plug.Looking at the back of the alt. with the white plug on bottom it is on the right side, as you stated closest to the bat. terminal.

Ahh, looking from the back, mine is on the left or top side.

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Unread 08-01-2008, 03:33 PM   #4
JeepHammer
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Quote:
Originally Posted by Mike Romain View Post
Folks, I have had a discussion with JeepHammer about the AC Delco alternator used in the later CJ's.

Basically over the last 15 years I have come across a lot of AC Delco 'SI' alternators with pin one and two on the white plug's connection reversed. Even on a Usenet auto tech group it has been noted as happening.

JeepHammer hasn't run across it.

I am up in Canada if that might make a difference.

In my case now, I am not sure which one I have in now, but my #1 with the solid core small wire or the excite is on the side of the white plug closest to the battery wire connection.

Where are your wires in the white plug?

I am curious as to how widespread this is.
Mike, I wasn't aware we had a 'Conversation' about this...
BUT,
I did note I hadn't see it before.
I have a couple of Regulator catalogs here
(out dated, but so is the SI alternator)
And none of them note the reversed terminals...

I was just wondering what the application was so I could look up the reversed terminals by application...

After I read about the reversed terminals, I stuck my nose in the 2000/2001 Delco reference catalog, and it lists the same wiring diagram I've been using for years...

AND,
It says "Delco Remy SI Series - All"

The only variation I see in the Delco books is for the 'Tach' terminal (3rd) terminal where the two wire plug fits for Fork lifts and such,
Or the 'Tach' terminal on the back for Stuff like diesel trucks...

I'm always interested in new stuff, so I was just wondering Where/What application used the reversed terminals?
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Unread 08-01-2008, 03:41 PM   #5
Mike Romain
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Quote:
Originally Posted by JeepHammer View Post
Mike, I wasn't aware we had a 'Conversation' about this...
Well, you have mentioned that to me twice unless I have you mistaken for someone else, so that almost makes a 'discussion' like I mentioned.

Let's have a conversation about it now. :-)

Quote:
BUT,
I did note I hadn't see it before.
I have a couple of Regulator catalogs here
(out dated, but so is the SI alternator)
And none of them note the reversed terminals...

I was just wondering what the application was so I could look up the reversed terminals by application...
If I remember right the first time I came across it was on an 80's FW drive OLds or Trans AM my friend Olof owned back in the early 90's.

My 86 CJ7 seems to have reverse wiring in the plug from the previous poster to this thread, Sparkey, with an 83 CJ.

Quote:
After I read about the reversed terminals, I stuck my nose in the 2000/2001 Delco reference catalog, and it lists the same wiring diagram I've been using for years...

AND,
It says "Delco Remy SI Series - All"

The only variation I see in the Delco books is for the 'Tach' terminal (3rd) terminal where the two wire plug fits for Fork lifts and such,
Or the 'Tach' terminal on the back for Stuff like diesel trucks...

I'm always interested in new stuff, so I was just wondering Where/What application used the reversed terminals?
See above and lets see how many more post where their excite is. Mine is on the left at the top looking from the back as the new photo shows.
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Unread 08-01-2008, 03:56 PM   #6
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Yup, that's a standard SI alternator... 12 SI to be exact, usually between 55 and 68 amps.
You can easily identify it by the larger rectifier (Diode) cooling holes, and the reinforcement gusset to the rear bearing boss.

If you look just to the 'Right' of the regulator cooling holes, you will find a 'D' shaped hole, this is a 'Test Hole'...
(NOT the small 'D' shaped cooling holes all the way around the outside of the case)

Stick a small screwdriver in there and ground the metal tab on the regulator to the case, and the alternator will put out at fully rated load!
DON'T DO IT FOR VERY LONG! It will overheat the rectifier diodes if you keep it at full output for very long, and it doesn't do the battery any good either!

NO DEDICATED GROUND WIRE TO THE ALTERNATOR!



Your alternator is a classic example of a Delco Remy SI series alternator...
Just like I show in all my drawings and wiring diagrams.
'#1' or 'Excite' on the left, '#2', 'Sense' or 'Sample' on the Right, 'BATT' terminal on the back...
'#1' or 'Excite' will need a resistor or Diode to work properly.
Many times, the resistance from an 'Idiot' light bulb will be enough.
Vehicles without an 'Idiot' light will use a Resistor Wire like you have in the picture, (Small, Brown, 10 to 15 Ohms),

The '#2' or 'Sense' wire is usually a 12 or 16 Ga. wire, and simply supplies the regulator terminal with a 'Sample' of 'Line Voltage'.
In your case, AMC/Jeep cheeped out and supplied it with a sample of the 'Battery' voltage, which is a short cut to properly wiring the regulator...

The #2 or 'Sense' wire should actually go to the interior of the vehicle, and take it's 'Sample' after the fuse block load, where all the electrical current load of the vehicle is.

*IF* you were to take your 'Sample' after the fuse block, Like say, at the horn relay or off the back of the gauge cluster, the volt meter wouldn't dive down when you turn on accessories like headlights, fans, ect... Since the 'Sample' would show a voltage drain and correct for it...
The way it's wired, all you get is 'Alternator output voltage', and there is an internal sample of that! The alternator doesn't need TWO samples of the same output voltage!

If you look jut 'Up' from the 'BATT' terminal connection in your picture,
or just 'Right' of the '#1' or 'R' terminal on the back of the alternator, you will see the hole where the 'Tach' terminal would be if you had one.

You are using the plastic fan, so if you switch this alternator with another one, you will need to swap the spacer behind the fan with the fan.
Metal fans use a different spacer than plastic fans...
------------------------------

I also see someone has patched in a fusible link to the back of the alternator...
That doesn't do you any good at the back of the alternator....

The fusible link needs to be at the starter relay 'Battery Cable' terminal...
The fusible link is there to protect the battery cable if the heavy wire to the alternator gets pinched, grounded and starts to burn.
The fusible link will burn, rendering that circuit 'Dead'...

If you have a fusible link in both places, that's OK too, but the lower one at the alternator isn't really doing too much...
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Unread 08-01-2008, 04:00 PM   #7
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Quote:
Originally Posted by Mike Romain View Post
Well, you have mentioned that to me twice unless I have you mistaken for someone else, so that almost makes a 'discussion' like I mentioned.

Let's have a conversation about it now. :-)
OK with me!

Quote:
If I remember right the first time I came across it was on an 80's FW drive OLds or Trans AM my friend Olof owned back in the early 90's.
Wasn't me, I would have told you that an early 90's GM vehicle would have had a CS alternator, not a SI alternator.
They (CS) are reversed from an SI connection...

Quote:
My 86 CJ7 seems to have reverse wiring in the plug from the previous poster to this thread, Sparkey, with an 83 CJ.
I don't know... Let's see,

Quote:
Originally Posted by sparkey View Post
I have an 83 with the I-6 engine and the small wire is on the #1 terminal of the plug.Looking at the back of the alt. with the white plug on bottom it is on the right side, as you stated closest to the bat. terminal.
Small Brown Resistor left or #1, Larger Red on the right (#2) in the plug.
Sounds pretty typical to me!

Quote:
See above and lets see how many more post where their excite is. Mine is on the left at the top looking from the back as the new photo shows.
I commented on that picture in a different post.
Your application is the typical SI alternator, nothing strange about it.
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Unread 08-01-2008, 04:20 PM   #8
Mike Romain
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Quote:
Originally Posted by JeepHammer View Post
OK with me!
Wasn't me, I would have told you that an early 90's GM vehicle would have had a CS alternator, not a SI alternator.
They (CS) are reversed from an SI connection...
They were mid 80's vehicles.

Could we be getting CI alternators sometimes instead of the SI?

Quote:
I don't know... Let's see,
Small Brown Resistor left or #1, Larger Red on the right (#2) in the plug.
Sounds pretty typical to me!
Right... upside down to mine....

Quote:
I commented on that picture in a different post.
Your application is the typical SI alternator, nothing strange about it.
Check the kink in my excite wire at the plug, that is from the swap I had to do from the last alternator.
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Unread 08-01-2008, 05:05 PM   #9
Mike Romain
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Quote:
Originally Posted by JeepHammer View Post
OK with me!

Here is one about an 86 Frebird, there are more.

http://groups.google.ca/group/alt.au...06f08ae19f302b
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Unread 08-01-2008, 05:34 PM   #10
sparkey
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Actually Mike mine is like the one in the photo. My plug is on the bottom where this one in photo is on top. I took a photo but see I can not post it here yet.
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Unread 08-01-2008, 09:25 PM   #11
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Quote:
Originally Posted by Mike Romain View Post
They were mid 80's vehicles.

Could we be getting CI alternators sometimes instead of the SI?
I would think so, CS alternators took over in the late '80's and continue through today....
SI alternators are mostly 'Farm Trucks & Fork Lifts' towards the late 80's.

Quote:
Right... upside down to mine....
Nope, same as yours....
Resistor wire closest to the 'Batt' terminal,
Sensor wire on the 'Right' from behind.

Quote:
Check the kink in my excite wire at the plug, that is from the swap I had to do from the last alternator.
Sorry, don't see any indication anything is reversed...
---------------------------

Just read through that posted thread, and here is the kicker...

Quote:
Checked terminals at starter R & S + big positive cable.
That would be a CS alternator with 'R' & 'S' markings...
SI alternators only had 'R' & 'F' or '1' & '2' markings.

He was trying to use the early CS alternator on a SI wiring harness...

That particular version of the CS alternator needed about 500 Ohms in the 'Excite' wire to keep it alive...
The SI system only has about 15 Ohms maximum...
I'll bet anything he's changing out the alternator every 30 days to two months now...
For $14 NAPA would have sold him an adapter to keep his alternator alive.

Last edited by JeepHammer; 08-01-2008 at 09:40 PM..
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Unread 08-02-2008, 08:37 AM   #12
Mike Romain
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Quote:
Originally Posted by JeepHammer View Post
I would think so, CS alternators took over in the late '80's and continue through today....
SI alternators are mostly 'Farm Trucks & Fork Lifts' towards the late 80's.
This is making more sense now.

Quote:
Nope, same as yours....
Resistor wire closest to the 'Batt' terminal,
Sensor wire on the 'Right' from behind.
I was meaning his case back is clocked differently than mine with his white plug on the bottom which made my initial take on his description wrong.

Quote:
Just read through that posted thread, and here is the kicker...

That would be a CS alternator with 'R' & 'S' markings...
SI alternators only had 'R' & 'F' or '1' & '2' markings.

He was trying to use the early CS alternator on a SI wiring harness...

That particular version of the CS alternator needed about 500 Ohms in the 'Excite' wire to keep it alive...
The SI system only has about 15 Ohms maximum...
I'll bet anything he's changing out the alternator every 30 days to two months now...
For $14 NAPA would have sold him an adapter to keep his alternator alive.
OK, would you please explain about this adapter.

I had a 'new' 'inexpensive' (3 mo warranty) rebuilt alternator in my CJ7 with the reversed pins for sure because I remember having to swap them as well as the evidence I left by kinking the wire when I pushed it into it's plastic clip.

That alternator failed really quickly, I figured mud killed it, then I got the current one with a 5 year warranty for a bunch more $$$$ and had to swap the wires again.
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Unread 08-02-2008, 09:03 AM   #13
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Quote:
Originally Posted by Mike Romain View Post
OK, would you please explain about this adapter.

I had a 'new' 'inexpensive' (3 mo warranty) rebuilt alternator in my CJ7 with the reversed pins for sure because I remember having to swap them as well as the evidence I left by kinking the wire when I pushed it into it's plastic clip.

That alternator failed really quickly, I figured mud killed it, then I got the current one with a 5 year warranty for a bunch more $$$$ and had to swap the wires again.
NAPA (among others) have short 'Pig Tail' adaptors,
They look very much like the sort adaptor in the pictures the guy posed on the other thread...

One end has a plug that fits your harness female
(that normally plugs directly into the alternator)

It has a couple of resistors inline to support the early CS alternators,

And it has a plug on the other end that plugs directly into the CS alternator.

They are made for all three common CS alternators so you can put a CS in place of a SI without cutting any wiring and replacing the plugs or moving wires around....
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Unread 08-02-2008, 09:17 AM   #14
Mike Romain
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Quote:
Originally Posted by JeepHammer View Post
NAPA (among others) have short 'Pig Tail' adaptors,
They look very much like the sort adaptor in the pictures the guy posed on the other thread...

One end has a plug that fits your harness female
(that normally plugs directly into the alternator)

It has a couple of resistors inline to support the early CS alternators,

And it has a plug on the other end that plugs directly into the CS alternator.

They are made for all three common CS alternators so you can put a CS in place of a SI without cutting any wiring and replacing the plugs or moving wires around....
Thanks, that does explain what I have been seeing over the years. I never realized the SI and CS had the different setups. The reversed wires are to prevent the wrong application.

It is something to watch out for though. The give away is the 1 and 2 or R and F pin labels vs the R and S labels. Anything else for a quick and easy difference ID?
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Unread 08-02-2008, 09:22 AM   #15
Mike Romain
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Quote:
Originally Posted by sparkey View Post
Actually Mike mine is like the one in the photo. My plug is on the bottom where this one in photo is on top. I took a photo but see I can not post it here yet.
I got that figured, you case back is just clocked differently than mine putting your plug at the bottom.
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