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how to install a saturn alt


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i found this in my hunt for information on this swap i did not do this nore do i take credit for the information contained im just posting it here so we have it on ratsun


I personally just did this swap in a 620 truck, the only difference would be that you wont have the idler arm clearance issue in a 510. There are many ways to do this so check it out.

A quick list of what you need,

a turnbuckle or a couple heim joints to make your own turnbuckle these can be sourced form most hardware stores

An alternator I usednapa PN: 213-4591 94 saturn SL

Probably need a new belt shorter or longer... I used what Motion auto supply listed as stock belt

etc etc

So, your alternator sucks well yea WE KNOW! here are a few alternatives that have been found.


Recently i put a saturn Alt in my 77 620, there are many different ways of doing this so i will try to include a multitude of pictures. I used an Alt out of a 94 saturn SL

napa PN: 213-4591

The price was about 50 bucks after I dishonestly gave them my Hitachi as a core :lol::lol:

The belt you will need is a V belt just like what you have on your car or truck right now. You may need a longer belt or a shorter belt then what you currently run. Me personally i used a belt that is listed as a stock belt for an L20b in the 77 620.

You will need to swap the pulley on the saturn alternator from the one that comes with it to a V-belt pulley, At your local parts main store they probably have a box of misc alternator parts. I asked them if they had any extra pulleys laying around and they sure did, i grabbed one that was about the same diameter as the saturn alt and put it on.

original pulley seen on the right


Okay to get the alternator to bolt into your truck you will need to modify the lower mounting bracket.

So start with draining your radiator and getting the lower hose out of the way! next unhook your battery and remove the old alternator and lower mounting bracket (thing alternator is bolted to)


Lets start here.




SECOND- cut shim! so that it doesnt over hang


Re-Insert shim



Next you will need to grind the lower mount, like so.


Basicly you are wanting to be able to attach the new alt and rotate the bracket around it in the largest range of motion available.

with out grinding the bracket would hit the Alt here.


personally i didnt have a problem with the stock bolt fitting through the eye of the new alternator but mike did so he had to drill out the eye to get the bolt through... no big deal!




So the point you should be at right now is... Your old alternator is out of the truck, your about 4 beers deep and thinking you dont know what your doing... okay lets show our selves some progress. put the freshly modified/fabricated alternator mount back in the truck and bolt it in. wheew okay we are on our way!

next bolt in the new alternator keeping the bolts loose so that you can move it around. check your clearances to see how much upwards and downward movement you have.

the next part is where there is alot of controversy, some people do it different ways... Oh well get over it there is several ways to skin a cat. Mike and myself did this the same why its cheap and easy.

Go to lowes and get one of these



the one i got was 3 bucks.

I ended up unscrewing one eye completely and cutting it down about a 1/4 inch to give maximum adjustment.

So i didnt take any pictures of this so ill do my best to describe it.

The original upper alternator bracket looks kind of like a bannana. lay it on a bench and stare at it for a second... okay keep reading, one end has a hole it it, and the other end has a slot for adjustment. there is a small wrinkle in it for where it bolts to the block. At the end of the adjustment slot left enough metal to keep the strength and i drilled a hole for where im going to mount the turnbuckle then cut the rest off. Mike did the same thing here are his pictures.

on the left is the slot going to the top eye of the new alt, and on the right is the hole that you are going to drill.



basically all you are doing is making an anchor point for the turn buckle.

so now you bolt in your turn buckle, i screwed in the turn buckle and bolted it up with the alt as close to the block as i could go so that all of my adjustment was away from the engine hence tightening the belt. after it was all said and done I had about 3/8 of an inch between the top of the Alt and the radiator hose and about 1/2 inch before i would hit the idler arm. I did not have to modify anything else mechanicly.

here is mine installed



okay now that the alternator is installed and your out of beer go ahead and sleep it off and finish the wiring in the morning...

okay good moring kids!

so you need to go to a junkyard and get a plug for the back of your alternator, i got mine off of a 96 and it works just fine. the plug looks like this


Slodat hooked me up with pretty much all of my wiring info... take the t connector that was hooked to the stock alternator and hook it up as follows

the L on the saturn plug goes to the black and white wire off the T connector, and the F on the saturn plug goes to the yellow wire. now plug it in that part is done.

you should have a larger gauge White and red wire that should be your positive wire, if you noticed on the back of the saturn alt there is a post, it says positive next to it. Hook the large white and red wire to that. There is also a threaded hole back there some where. I found a matching bolt and hooked the black ground there.

Okay now get another beer and your almost through! find the voltage regulator, i took the regulator off the fender well and i cut the 4 wires that i was spliceing as close to the back of the regulator that i could. I spliced them and then tucked them back up there. It all looks stock from the outside.

So you are going to be splicing the yellow to the white wire and the White and black wire with White and red wire. just jumper them together.


okay thats it kids, double check all your connections hook your rad back up and your battery. now when you turn your key on your CHG light should come fire it up and check it with a volt meter.

for those of you that like wiring diagrams... here you go


thank you everyone for all the help with my install and I hope this thread did a decent job condensing the information about this swap


i found it rather helpful im more then likly going to the yard tomorrow to get the stuff to make it happen i hope this helps many people on ratsun

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i just picked up two saturn alts from pick-a-part, got the wire harness for one and a pully and turnbuckle for both, going to go pic up some belts and try this on the KC if all goes well the 710 will be next.

I think i got the whole thing down, the wiring part is a little intimidating but im sure i can fig it out.

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  • 2 months later...

so i got a saturn alt swap has same plug as pic above but has 4 wires, any ony know the wiring on this




i belive its red wire to the post on back

next two the same as above

last wire?


would like to install this


slodat where are you.....help.....anyone

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does that look right?


everytime I see this it changes. Yours has 4 wires on the blk plug with the big batt wire to the batt output? Never seen that one before.. Others I have seen 3 and in the earlier photo 2.


i think be ezer to get a hardbody alternator and get the connector from that then short the old volt reg with jumper wires.


well i bought this from slodat, it was on his dime....he told me how to wire it ...it was easy but its been awhile and i cant remember how.....i need to try to find his # then i could get r done....

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"generally" the "s" terminal is the sense wire, and can be connected to battery voltage. The "L" terminal is for the lamp, and would be coonected AS a ground to your charge lamp circuit. "F" is for field, or the voltage that passes through the rotor and brushes. Usually this is just a terminal on the alternator, and you leave it alone. I'm not sure why you have an "f" wire in the pigtail. I'm not sure what the "p" terminal is for. At any rate, usually the alternator is turned on through the lamp circuit. So you should really only need to use the sense and lamp wires to get the alt charging.


On a side note in reference the Hainz, you can use all the way up to a 2004 frontier 2.4 alternator. They bolt in, and only require the "t" connector to be adapted to the new style connector.

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  • 2 months later...

I have been pulling the parts together to do this swap. and the GM plug I got at the parts store has 3 wires, a larger red in the "S" position, a smaller black in the "F" position and a smaller brown in the "L" position. so not wanting to test my fire extinguisher I've done some searches on line and found some good info. the "L" & "F" wires are pretty well documented on hear, but the "S" (Red wire) was not. Apparently this wire will control the out put of the alt. it is best (or so I have read) to have this connected at the main power junction or distribution block location. it will sense the draw of your car and adjust automatically. here is some info on the CS130 alt connections, hope it helps...




Unlike other charging systems which have three wires connected to the alternator, the CS-121 and CS-130 may be used with only two wires connected to the alternator. The output wire to the battery positive, and an "L" terminal wire connected to the charge indicator bulb, or to the resistor, or to both.The charge indicator works in much the same way as on other charging systems-the indicator lights when the switch is closed, and then goes out when the engine is running. If the charge indicator is on with the engine running a charging system defect is indicated. For all kinds of defects, the indicator will glow at full brilliance. A new feature of this regulator is that it will cause the charge indicator to be on with the engine running if the system voltage is too high or too low. The regulator is temperature-compensated; that is, it's voltage setting varies with temperature. As in other alternators, the regulator limits the system voltage by controlling the rotor field current. Unlike other regulators, this regulator switches the field current on and off at a fixed frequency of about 400 cycles per second. By varying the on-off time, the correct average field current for proper system voltage control is obtained. At high speeds, the on-time may be 10% and the off- time 90%. At low speeds with high electrical loads the on-off time may be 90% and 10% respectively.The use of the "P", "F", and "S" terminals is optional. The "P" terminal is connected to the stator, and may be connected externally to a tachometer or other device. The "F" terminal is connected internally to field positive, and may be used as a fault indicator. The "S" terminal may be connected externally to a voltage, such as battery voltage, to sense the voltage to be controlled. For complete circuit, reference must be made to the vehicle manufacturer's wiring diagrams.

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  • 1 month later...

sorry if this is outdated or anything but i bought one of these alts todays and i bought the plug for it as well, my plug is 3 wire with the red in the s position and the other 2 in the f and l position, which is the ground for my light and where does the red go? to the back of the alternator or somewhere on the positive battery side (after the battery somewhere so it can sense the current?) i want to get rid of my stock regualtor since this one is internal, hoping to clean up the engine bay a bit!!! thanks

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Ref: copied on-line info: from copied sight: http://en.allexperts.com/q/Chevrolet-Repair-808/1987-Corvette-alternator-wiring.htm


"P" Terminal (Phase Connection) - This terminal sends a signal to a relay, frequency sensing tachometer, or computer indicating alternator speed. This terminal may not be used - this is normal.

"L" Terminal (Charge Light) - This terminal is fed from the ignition through the charge light on the dash. This connection turns the alternator "on". Without a signal to turn "on", the alternator will not charge. However the "I" terminal may be used to turn this alternator "on", as described, instead of the "L" terminal. Please note that if there is a connection on the "I" terminal there will be NO connection on the "L" terminal.

"I" Terminal (Ignition) - This terminal is fed directly from the ignition switch to turn the alternator "on". Without a signal to turn the alternator "on", the alternator will not charge. However the "L" terminal may be used to turn this alternator "on", as described, instead of the "I" terminal. Please note that if there is a connection on the "L" terminal there will be NO connection on the "I" terminal. If there is a connection on the "L" terminal AND the "I" Terminal THEN the "I" terminal is NOT an "I" terminal but an "F" terminal (confused yet?).

"F" Terminal (Field Monitor) - This terminal sends a signal to the computer telling it how much field current is flowing (therefore the computer knows how hard the alternator is working). This terminal is not always used AND can only be used if the alternator is turned on by the "L" terminal.

"S" Terminal (Battery Sense Connection) - This terminal is larger than the others and provides the alternator with a precise battery voltage reading however, this connection may not used. When not used, the alternator will automatically sense battery voltage at the battery post.



Started typing all that shit...then decided to search. Found that.




The way I learned it...


You only need the F (Field) to tell the alternator to start charging and the L (Light) to tell you when it's not working. My saturn alt only had the feild hooked up and it worked fine.



I also never had to grind on my alternator mount but my truck was a 77, I think the earlier brackets are different.


I hooked my KA alt into the pink trucks system using this thread for the Datto wiring stuff, to bypass the regulator. Worked awesome thanks Bonvo for getting most of it in one post :D

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