Important: Improvements on Saturn Alternator Swap

[turboglenn]

I didn't know where to put this just yet so i started here since it is a bit custom. The Original article can be found HERE

UPDATE/EDIT: YOu can getthe plug at any advance or oreilly auto parts.. you have to ask for a 'GM "CS alternator pigtail... they won't find it looking up "saturn"

above is the method I used to swap mine. There was however a problem with the wiring in this and every other write up on tuners and talk forums.

All existing how-to's say that the black yellow wire on the mitsu harness goes to pin "L" this is true as this is one way that the alt turns on and becomes active, but this circuit MUST HAVE AT LEAST 35Ohms resistance and up to 350 max. (which it does) and this wire alone is enough to work the alt besides the main power feed wire for charging.

However here's where things get off track.. The articles say to hook a switched 12 volt to "pin F" ...This is not really wrong but doesn't do anything! IT is ONLY another way to start the alternator should you not have a "battery lamp" wire that has the 12v with 35Ohm resistance to it.... The "F" terminal is for field and it has it's own resistance built in internally so i've read, but either way it doesn't need a resistor or buib and it starts the alt charging just like the black/yellow battery light wire does..

Now the alt will work OK with it wired this way but after scruitinizing the voltage at all times both on a data logger and FLUKE voltmeter since i did the install i can only say i was less than pleased with the output...sure it was better than OEM but nothingn to write home about. So i set about reading for probably 6 hours in 2 days and calling some of the top high output alt guys listed on the web. That's where i learned about "F"

The important wire is "S" this is the wire that reads the voltage at what ever given area it's attatched to and either lets the alt shut down a little or makes it work harder. And sure it will work withtout it but just not up to my standards or anyone like me ...Most people say loop "S" back to the +batt terminal on the alternator, but the problem with that is it's always going to read 14volts and not adjust at all.... The issue withour cars is voltage drop in the rest of the system and as we all know poor grounding.

Tonight after learning all of this i tore into alternator wiring and just finished with awesome reasults... Here's what i did ... I left the "L" wire hooked up... Pulled the fuse on my "F" wire line just in case i wanted to put it back some day and it was nicely tucked... Then i took "S" and soldered a length of 12 gauge wire to it and routed it back across the car and tied it into my distribution block where it could sense the "dropped volts" and also see how low the main system was getting under load. Then i took a length of 8 gauge wire and mounted 2 ring terminals on the ends.. One end got bolted to the hole in the back of the alt (obviously there for a ground IMO) and then hooked the other end to the main ground from the battery that hooks up at the trans.

I snugged everything up and started the car.. I took a voltage reading at the battery ..14.7 volts..NICE! Then i turned on EVERY accessory the car has..lights, A/C radio, rear defog, wipers, and hazards... And not a single flinch from any thing (normally i can tell low volts because my tach adapter makes my tach go nuts when the volts drop too low) I went back and checked the voltage again at the battery and it was 14.5 I could not have been happier and this was at IDLE..normally to get it back up the old wiring way i had to rev the car and it still would not make 14volts... Now it does it at it's low chugging with the AC on idle

HOpe some of you with saturn alt swaps check what i'm saying and log your volts or check with everything on... if they're fine, cool... If not you now know how to make it right !!

 

[ApexVIII]

i am working on my Saturn Alt Swap too,

i t has been in for about 2 months, better then the stock one for sure, but i have noticed that when my headlights are on and the AC is on, i can get the voltage to dip to low 12's and sometimes even high 11v

how exactly did you run each wire? did you pick up a new pigtail that has 4 wires comming out of it? because the OEM Saturn one i have only has 2 wires comming out of it


oh the reason i am messing with the Alt. is i found that i am getting a .5amp drain when everything is off(car not running) and the Alternator is making a slight humming sound when the car is off

 

[snowborder714]

What alternator (where'd you get it and it's amperage) are you using Glenn?

 

[twack]

apex that is the signal wire, you have a constant signal going to the alt wich leaves it on at all times. you either need to switch it to a on off switch or so a wire that turns on with the car

 

[ApexVIII]

apex that is the signal wire, you have a constant signal going to the alt wich leaves it on at all times. you either need to switch it to a on off switch or so a wire that turns on with the car

ok thats what i thoguth, so i need to run a switched power wire to the "L" wire on the alternator?


so what color is the "S" wire? its on the stock harness correct?

 

[My1GLaser]

Then i took "S" and soldered a length of 12 gauge wire to it and routed it back across the car and tied it into my distribution block where it could sense the "dropped volts" and also see how low the main system was getting under load.

You are the man!

I assume this "S" is on the Saturn plug. Can I just run it to the fuel pressure solenoid harness area where I have the "F" hooked up now? I don't have a distribution block. God I hope this works. Maybe I can sell my boost-a-pump if it clears up my voltage issues. I installed it just to keep constant voltage at the fuel pump so I would have stable AFR thru the whole rpm range.

 

[turboglenn]

The plug is a "universal" plug for any GM "CS type alternator" it has 3 wires one for "L" one for "F" and a large red one for the "S" GO to advance, NAPA, or O'reilly and just tell them you need a plug for a GM "CS" alternator and you will get one with 3 wires black for the "L", brown for the "F" and red for the "S"

snowboarder... I'm using a 96 saturn SC2 alternator and the pigtail was picked up at O'reilly I will try and get a part # tonight. It is truely 96 amps and not the 160/130 o r other reading you hear about.. Now you can go buy a CS-130 alt and it is 130 amps but the thing is thatit doen't have the same tabs on it to make it easy to bolt to the car...

I may start making an adapter kit to properly wire the car so people dont' have to guess about where things go, but we will see... If i could find some junk dsm alternators i could make a plug-n-play harness


another interesting fact is that the "P" pin (not used) is to drive a tachometer to read out the RPM of the alternator its' self but requires a special tach to read is signal it's a half wave 7 volt positive.

APEX..... ONLY RUN THE BLACK WITH yellow stripe to the "L" wire it stands for "light" as in the dummy light and if it doesn't have at least 35 ohms resistance you will fry the alternator on the spot... ( THIS is why we have the "alternator relay" it's not really a relay but a resistance box to add some more resistance over the dash bulb) The "F" wire is the one that does not need a resistor and both the "L" and "F" serve the same purpose and that is to activate the alt... ALso there is no "S" on the mitsu side of the harness you must lengthen it and run it to the area where the battery, alternator and starter wire connect

IN all a honesty on our cars you ONLY need the"L" sourced wire from the dummy light wire on the mitsu harness (black with yellow stripe) This is the best way because it will tell you that the alt is working when the dash light goes out when the car is started. THere is no need for the "F" wire but it can be used.. the reason some plugs don't have the "S" plug is that it can cause a large amount of voltage to be sent to the electrical system in the saturn which it cannot handle.

Run the "S" wire to your distribution block where your accessories get power from

I will make a diagram tonight as well showing the ultimate way for best charging to hook up this alt.

Mise is frickin unbelievable in the way it produces power.. I was getting 14.5 at only about a 600 PRM idle :YEAH:

Here's the schematic showing how the wires run together although this on shows the dummy light wire labelled as "field" it doesn't mater because the "F" and "L" do the same function and both tie to field and that's to turn the alt on...the "L" is just a marking to let you know that's for the "light" on the dash. The dash light has 12volts coming from it and when it hits the alternator it turns it on...then if the alt fails the "L" goes to ground lighting up the "batt" light on your dash... DO NOT USE THIS "L" pin without a resistor if you don't use the dummy light wire...but i highly suggest using the dummy light wire as it's the best way to activate it with a read back of what's going

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This diagram is for an "SI: alternator which is also commonly upgraded to a "CS" alt, and aside from it not having seperate "L" and "F" wires the hookups are the exact same principal

 

[turboglenn]

My1glaser... IF you don't have a distribution block do this... wire the 4 gauge from the alt direct to the starter, then wire the battery direct to the starter and pull the accessories leads from the starter post as well, then add the "S" wire to that connection and you will get the same effect.

You do not want to hook it to one of the regulated 12v wires for a solenoid or sensor as it will keep reading the regulated 12v and never hit the 14 that it wants to see, then it will think its is a low voltage situation, make the alt work harder and cook your wiring... It needs to be tied into the main power wires either at the starter or directly to the battery will work as well...the distribution block is a trick chevy started using in the late 60's early 70's to get the best performance from the low tech alternators they had back then.

 

[ApexVIII]

how did you route the wire to tap in to the stock FPR for the switched 12v? and what wire is the switched 12v there ?

 

[juanpac0]

Glenn, I have 2 junk dsm alts I'd be glad to donate if it means helping me and others with this swap. I'm planning on putting a nice sound system in my car later (nothing crazy, just way better than the crappy stock system) and I want to minimize voltage drop.

I'm planning on regrounding my engine bay and rewiring my fuel pump as well, but this would be the icing on the cake. Shoot me a PM and we can work out shipping or something.

 

[turboglenn]

how did you route the wire to tap in to the stock FPR for the switched 12v? and what wire is the switched 12v there ?

My car is complete stand alone.. All the emissions crap and solenoids and their wires have been removed from the harness.. I don't run a "switched 12 volt" (and when i did i just wired it from an accessory in the fuse box, and i don't know what one,...just use a voltmeter and find one) But you don't need it anyway, that's what the black/yellow wire from the dummy light is for and it goes to "L" ...... then the "S" from the alt goes to your accessory hookup area, junction block, distribution block what ever you have, you can even hook it to the battery or back of starter


But my whole point in this thread is to say that the switched 12 volt to the "F" is ONLY needed if you don't have a dummy light and unless your car is a gutted race car with no dash then you have the needed wire to activate it..the switched 12 is NOT NEEDED.. if you have the black/yellow then the switched 12 does no good the impotant ones are the black/yellow annd the "S" 'sense" wire to get proper charge

 

[ApexVIII]

My car is complete stand alone.. All the emissions crap and solenoids and their wires have been removed from the harness.. I don't run a "switched 12 volt" (and when i did i just wired it from an accessory in the fuse box, and i don't know what one,...just use a voltmeter and find one) But you don't need it anyway, that's what the black/yellow wire from the dummy light is for and it goes to "L" ...... then the "S" from the alt goes to your accessory hookup area, junction block, distribution block what ever you have, you can even hook it to the battery or back of starter


But my whole point in this thread is to say that the switched 12 volt to the "F" is ONLY needed if you don't have a dummy light and unless your car is a gutted race car with no dash then you have the needed wire to activate it..the switched 12 is NOT NEEDED.. if you have the black/yellow then the switched 12 does no good the impotant ones are the black/yellow annd the "S" 'sense" wire to get proper charge

ohhh ok got ya!

 

[ApexVIII]

alright i just finished rewiring my Saturn Alt. i am getting 14v at idle nothing on,

if i turn on the stereo headlights (HID's) and AC i can get it to go to high 12's where before it was low 12's so its alot better

i ran a 10gauge wire from the S to the battery + post

 

[turboglenn]

alright i just finished rewiring my Saturn Alt. i am getting 14v at idle nothing on,

if i turn on the stereo headlights (HID's) and AC i can get it to go to high 12's where before it was low 12's so its alot better

i ran a 10gauge wire from the S to the battery + post

Did you use a new 4 gauge wiure from the alt to the fuse-box or battery? The OEM dual 8 gauge wires drop a good bit of voltage...also did you ground the alternator to the same point as the battery ground at the trans case? each one thing yielded me like one more volt at a time until i has done all 3 (sense wire at dist. block, 8 gauge ground from alt to trans case w/ battery ground and 4 guage wire from the alt)

Run that "S" to the accessory terminal in the fuse box and i bet it gets even better... also the saturn pulley is larger than the mitsu one so try putting the RPM's up to 1100.. I get a lot better voltage even with the sense wire at the battery if i raise the idle just a tad... I am alsmot sure you canget back near 14 volts with it some how... I played with where i put the "S" wire and noticed that if i put it on wires that had more drain on them i got better voltage, if i put them on a circuit that saw very little draw/drop i only got slightly better volts ( i played with it more tonight for the purpose of being able to correctly inform others)

 

[ApexVIII]

i ran a 10 gauge from the "S" all the way to the battery, took almost 9' of wire

i ran a 10 gauge ground but i grounded it to the frame on the radiator support,

i probably should run a larger gauge ground to the main grounding point also.

do you think the "S" wire(10 gauge) is large enough going to the battery?

by dual 8 gauge, do you mean the actual wires that are comming off of the Positive terminal on the alternator?

 

[turboglenn]

i ran a 10 gauge from the "S" all the way to the battery, took almost 9' of wire

i ran a 10 gauge ground but i grounded it to the frame on the radiator support,

i probably should run a larger gauge ground to the main grounding point also.

do you think the "S" wire(10 gauge) is large enough going to the battery?

by dual 8 gauge, do you mean the actual wires that are comming off of the Positive terminal on the alternator?

Yes, by dual 8 gauge i mean the 2 white OEM wires. Alsothe "S" wire should be a smaller gauge (12 or smaller) as having more resistance in and will cause the alt to charge more as it will even see voltage drop from that wire. I read up a ton on this stuff over the last few days and chevy actually used damn near 10 feet of 12 gauge wire to the junction block ( 4 way crimp) on their older setups to make the alt charge hard enough to keep the coltage high at all times to the points that were suffering voltage drop. If anything re-locate the "S" wire some where a little more in-direct in relation to the battery and go with a smaller wire. I put mine at the distribution block where my AMP, accessories, fuel pump,. J&S, N20 and meth injection get their power from. And at that sam,e block is the 2 white wires that feed the accessories from the fuse box like wipers, radio, hornm blower motor etc... Basically if you tie it into a place that has a higher number of things pulling voltage or where ever you can measuer the lowest voltage that isn't regualted down the better the alt will charge. That's about the best i canexaplin.... Just google "converting to CS alternator" or GM alternator wiring and any combination of saturn, GM alternator, sense wire, GM alternator and so on.. You cna read for hours like i did and then you will be answering questions and know exactly what you need to do with your wiring

Look up madelectronics alternators, they have a TON of usefull info although sometimes hard to find or you have to read every link on thieir page, there's enough out there to fill a set of books

 

[airmail96]

Awesome write-up glenn. Can't wait to do this on my next dsm along with the alt relocation.

 

[turboglenn]

Well, after 5 days of steady use, lots of day and night time driving with the A/C, light and radio (and half the time wipers) all being on I am still seeing constantly better voltage staying in the 13.7 - 14.2 range depending on the amounf of accessories on and the RPM. At an idle of 7-800 I was seeing lower volts as well (sometimes high 12's) but after bumping the idle to 1000 - 1100 i can see a full 13.9 with everything on.

Just wanted to update after a week of use to ensure everyone that this is still working great with the new wiring!

 

[juanpac0]

Glenn, I should have all the stuff shipped out to you this week so you can make a harness, I also shot you a PM.

 

[knochgoon24]

I just picked up an alternator today from the pic-a-part yard near my place for $30. It tested A-OK at Advance Auto on their fancy little machine.

It doesn't look exactly like the one in the write-up, but it's very very similar.

 

[ApexVIII]

Yes, by dual 8 gauge i mean the 2 white OEM wires. Alsothe "S" wire should be a smaller gauge (12 or smaller) as having more resistance in and will cause the alt to charge more as it will even see voltage drop from that wire. I read up a ton on this stuff over the last few days and chevy actually used damn near 10 feet of 12 gauge wire to the junction block ( 4 way crimp) on their older setups to make the alt charge hard enough to keep the coltage high at all times to the points that were suffering voltage drop. If anything re-locate the "S" wire some where a little more in-direct in relation to the battery and go with a smaller wire. I put mine at the distribution block where my AMP, accessories, fuel pump,. J&S, N20 and meth injection get their power from. And at that sam,e block is the 2 white wires that feed the accessories from the fuse box like wipers, radio, hornm blower motor etc... Basically if you tie it into a place that has a higher number of things pulling voltage or where ever you can measuer the lowest voltage that isn't regualted down the better the alt will charge. That's about the best i canexaplin.... Just google "converting to CS alternator" or GM alternator wiring and any combination of saturn, GM alternator, sense wire, GM alternator and so on.. You cna read for hours like i did and then you will be answering questions and know exactly what you need to do with your wiring

Look up madelectronics alternators, they have a TON of usefull info although sometimes hard to find or you have to read every link on thieir page, there's enough out there to fill a set of books

do the 2 oem 8 gauge wires fro mthe alternator go to the battery or the fues box?

if they go to the battery did you just loop it around the back of the motor to the battery?

im trying to decide how much feet of what gauge cable i am going to need to do some more of the rewiring

i assume probably 10ft of the 12gauge for the "S" plug

10ft of 4 gauge to the battery from the alternator

10ft of 8 gauge for the battery ground

that sound like enough?

 

[turboglenn]

do the 2 oem 8 gauge wires fro mthe alternator go to the battery or the fues box?

if they go to the battery did you just loop it around the back of the motor to the battery?

im trying to decide how much feet of what gauge cable i am going to need to do some more of the rewiring

i assume probably 10ft of the 12gauge for the "S" plug

10ft of 4 gauge to the battery from the alternator

10ft of 8 gauge for the battery ground

that sound like enough?

2 two OEM wires went around the radiator support and connected to the fusebox, I ran my 4 gauge wire to the same locations, as for the "S" wire i used about 7 - 8 feet of 10 gauge at first but after more readings from the voltmeter and datalogger i swapped it down to 12 gauge and saw more improvements

You will have well more than enough with your estimates on wire

I used 4 guage everywhere from alt to fuse box, then from fusebox to battery and battery to alt. All together i think i burned up about 15 feet of 4 gauge getting the job done.

 

[My1GLaser]

Did you use a new 4 gauge wire from the alt to the fuse-box or battery? The OEM dual 8 gauge wires drop a good bit of voltage...also did you ground the alternator to the same point as the battery ground at the trans case? each one thing yielded me like one more volt at a time until i had done all 3 (sense wire at dist. block, 8 gauge ground from alt to trans case w/ battery ground and 4 gauge wire from the alt)

Run that "S" to the accessory terminal in the fuse box and i bet it gets even better... also the saturn pulley is larger than the mitsu one so try putting the RPM's up to 1100..

I hadn't done the 4ga wire from the alt-->fuse box-->batt and I was seeing some improvements already. But when it got dark and I turned on my lights, the volts went down to 12.19 at idle and wouldn't come back up to 13.58 until I hit the gas. (It logs .3 volts lower than at the battery.) I just ran 4ga wire yesterday and ran an 8ga ground back to the batt. I have a couple extra 4ga & 8ga grounds around the engine bay also. I will take it out for a run later and see how it does.


I used 14ga for the S wire b/c thats what I had laying around. I ran the S wire to the batt pos terminal. What is this accessory terminal in the fuse box that you are talking about? I might want to try that if I don't get the results I want to see this evening. What about swapping to a slightly smaller diameter pulley?

 

[ApexVIII]

2 two OEM wires went around the radiator support and connected to the fusebox, I ran my 4 gauge wire to the same locations, as for the "S" wire i used about 7 - 8 feet of 10 gauge at first but after more readings from the voltmeter and datalogger i swapped it down to 12 gauge and saw more improvements

You will have well more than enough with your estimates on wire

I used 4 guage everywhere from alt to fuse box, then from fusebox to battery and battery to alt. All together i think i burned up about 15 feet of 4 gauge getting the job done.

ok. i picked up that wire over the weekend, and will work on it some more today,

did you leave the stock 2, 8gauge wires? and install the 4gauge? i think im going to do that just so they are there. cant hurt right?

 

[turboglenn]

yea, i cut them off as short as i could. I didn't feel like getting into tearing the wiring out until i knew i was going to be satisfied with the new stuff.. Then once it tested out good, i just snipped them until my next rewire job which i'll probably do twice before winter