Alternator wiring - GTO specific

Question for those of you who've used the GTO LS1 motor and alternator.

I'm having some issues with the wiring for my alternator. I'm running a 2004 GTO LS1 with the GTO alternator. The PCM and wiring harness is F-body specific from SSP. It has 1 red wire labeled 'Alternator'.

The first way I wired the alternator had the red alternator/PCM wire connected to the A terminal on the alternator, and the B terminal of the alternator jumped to the rear + battery post at the rear of the alternator. This resulted in overcharging and draining the battery with the car not running.

I've tried a couple different ways to wire the alternator but keep finding some combination of the same issues. Current draw (with the engine not running) and overcharging (with the engine running).

The wiring harness I have has 1 wire from PCM to the alternator. My tuner is saying that the alternator does not need to be connected to the alternator.

The current way I have it wired:

Terminal A - fuseable link to the + Batt post at the rear of the alternator
Terminal B - not connected to anything
+ post at rear of alternator is connected with a 2 gauge wire to the battery +

With this wiring the alternator charges at 14 or so amps according to the 944 gauge cluster. However, with the car not running, the alternator is warm to the touch and the battery drains within hours.

One thought is whether I need to connect the Terminal B to switched 12v power. Will that fix the draining issue?

Note, the alternator is a newly rebuilt and the battery is also new.

Any suggestions?

Thank you!
Dan.

I'm not sure if this applies to the LS1 alternator. I have a LT1 with a CS130 alternator; I know I had to hook up one of the wires on the alternator to the stock porsche harness... I think it was a small blue wire (the one thats with the thick red starter wire). I think this tells the alternator when to turn on and provide the resistance it needs to work properly?

Just hook a wire from the post on the back of the alternator to the battery. Should be large , around 6 to 8 gauge. the PCM should have wire ran to the plug for the Alternator. If it does not call SSP , they are the ones that made the harness, get them to help you with the hook up. The LS1 alternator set up is different than the LT1, If you try to use the Porsche factory wire, you will burn up the alternator!

Thanks guys - here's where I am today.

I'm getting advice from both my tuner and some limited advice from SSP. Both have provided the same diagram - but I'm electrically illiterate and simply don't know how to decipher the diagram.

What I'm hearing from the tuner is the GTO alternator is a stand-alone system and shouldn't need to be connected to the PCM. I can't get SSP on the phone to answer my question directly - they are telling me to refer to the diagram below.

I couldn't find a way to post a PDF here - so a link to a hosted image:

http://944x2.blogspot.com/2011/03/alternator-wiring.html

I'm wondering if I need to connect terminal B to switched power in order to complete a circuit?

As it is currently wired, it seems to be charging fine, but when the car is shut off the alternator drains the battery and is warm to the touch.

Again, thanks for the input guys!
Dan.

The GTO alternator is a different beast than the normal LS1, it is also 140A. They are correct, it does not require the connection to the PCM to provide voltage regulation. Big wire to the starter as described, white wire to a +12V switched, and brown wire is for the dash idiot light. Watch the connections at the starter, it's easy to hit the headers or the engine block with it. Speaking from experience on that one.

Hi Mike,

Thanks - I was hoping one of you GTO guys would help out.

Let me get this straight...just to confirm. The reason I ask is that I'm hearing a different answer from each person I've asked. However, I'm much more inclined to go with 1st hand expereince and that you have.

Ok...

Post at back of the alternator goes to the starter, not the + battery post? (I have it routed to the + battery terminal currently)

Terminal A (guessing this is white...I don't have colors to refer to, only A/B) - goes to a 12v switched
Terminal B (again, I don't know the color references) - goes to the dash idot light? I disconnected the idot lights...previously. Do you literally mean the big '!' light? If so, which terminal? You wouldn't happen to have a picture or some reference to a diagram?

Sorry to be such a dolt with this stuff. Other than this issue, the car is fantastic!

Thank you much,
Dan.

Is there any use for the blue alternator wire coming from the Porsche firewall?

Not sure about the blue wire, but I'm not using it.

Somehow the 944 alternator gauge is working even though it is not directly wired to the alternator, so I'm assuming it's connected directly to the battery.

During this whole, long conversion the wiring and electrical hocus pocus has been one of the most mysterious elements to the process. If I were more motivated I'd get myself better educated on electronics and wiring. It's all a bit abstract to me, which I'm ok with as long as the car is running.

Dan.

The battery wire can go to either the starter cable or the battery post, same end result. Although in really rare occasions, I have heard that running it to the starter can cause a "run on " problem. Mainly in Ford though.

Like Admin said, the post at the back of the alternator can go to the starter or battery. It's just a shorter run to the starter. You are correct on the A/B designations. No I didn't mean the ! light. You have a voltmeter in the dash, you can ignore the B connection to an idiot light. If I remember right, the blue Porsche wire can be used to connect to terminal A as a + 12 source. It's been awhile since I looked at my wiring. I'll be back out there this weekend and will take a look if you need me to.

If he doesn't need the info, I do. Finishing the wiring is my last step to start this, hopefully in the next couple of weeks.

Ok - that's good info. Much appreciated.

Mike, if you don't mind having a look and writing down the A/B connections, that would be fantastic.

As currently set up, my alternator seems to be charging fine. It's drawing current with the ignition off though. Just a guess, but perhaps that means B needs to go to a switched +12v in order to close a circuit?

If the blue wire is an easy way to access switched +12v, that beats running another wire to the ignition.

Again, thanks for all the input guys!
Dan.

Ok, just finished a bunch of work on the car and was able to take a look at the alternator wiring. I did not use a blue wire, the GTO harnesss has a +12V white wire to the alternator. I ran the brown wire to the Porsche idiot light wire, I couldn't see what color that one was. Sorry no answer for the blue wire.

Mike,
Thank you for taking time to look at your setup. The man difference I'm faced with is the PCM and harness I have is F-body. I may need to return the GTO alternator and get a Camaro instead.
Again, thank you for looking into this.
Dan.

Hi Dan,
You're welcome, I'd think about keeping the GTO alternator, especially if you have a stereo or electric waterpump in mind, it puts out much more current than the fbody. It's pretty straight forward to connect up the +12v, you could probably tap off one of the pink wires in your harness, and just put a fuse or fusible link in line. I have the GTO schematics and electrical diagrams, I'll check on where they pick up +12v for the white wire.

Mike,
Yes, the GTO is 140 amps vs 110 that I saw listed for the '01 Camaro. I don't currently run any accessories, but may add some fans in the future for oil and trans coolers. Apart from that, it's a track car, so unless we run enduros some day, my charging needs are probably not extreme.

That would be great if you have a schematic.

Currently: The big post at the back is connected to the + battery, so that's 1 out of 3 that we know is correct. Aside from that, there are only 2 other connections. Currently the A is connected with a fuseable link to the post at the back of the alternator, and B is open.

With it hooked up this way, it charges when running but when not running the alternator is warm to the touch and drains the battery.

...sorry, I'm repeating myself.

As I write this, I found an instruction sheet that came in the box with the alternator. Picture link to my gallery below. This appears to be sort of generic, but I'm going to give this wiring a try. It's saying that "L" (what I have been referring to as "B") needs switched power. This may be the ticket.

Again, thank you for your guidance...as I flail with this relatively simple issue.

Dan.

https://944hybrids.forumotion.com/gallery/Personal-album-of-Dan-J/alt-wiring-pic_1367.htm

How many wires go into the plug on the alternator ?

Hi Admin,

2 wires, white wire terminal A goes to +12v, and after checking the schematic, it is wired directly to the battery through a fusible link, so always on. Terminal B brown wire is the charge indicator which needs +12 and is hot when ignition is on. As I am not on the road, I need to verify what I have done is correct with the idiot light. However, my alternator does not get hot or my battery drain down when the ignition is off. When the engine runs, I see the appropriate charge voltage. So I think all is well.

Good info Mike. Your wiring seems to correspond to the diagram that was included with my alternator. I totally disregarded that paperwork when I hooked it up.

I posted a picture of the alternator terminals in my Gallery. Don't pay attention to the wiring in the photo, this is before I knew not to connect the PCM (small red wire on A) and jump the B to the + post.

https://944hybrids.forumotion.com/gallery/Personal-album-of-Dan-J/img-0142-pic_1368.htm

Mike - I'll connect the B terminal to switched power and let you know if that solves it. Maybe that B terminal shuts off the circuit to the battery when the switched power is off? That might explain why the battery drains on mine but not yours. If your way is correct...I'll need to know what style beer you prefer, and your shipping address.

Thanks,
Dan.

Ok, here's the conclusion for wiring the GTO alternator...

The alternator is internally regulated and does not connect to the PCM - at least in the case of using an F-body harness/PCM

Terminal a is bridged to the main + post at the rear of the alternator
Terminal B is connected via fused link to switched +12v power (I used an extra slot on the fuel pump fuse/relay)
+ Charge post connected to + Battery

That seems to be the answer. Wired this way, the alternator doesn't drain the battery and indicates a charge (but not overcharge) when the car is running.

For a diagram, see my gallery.

Mike & Eric - kudos to you guys for your help!

Now I can focus on transmission and engine oil coolers!

Thanks,
Dan.

I thought I would update this thread since there seems to be some wrong information posted. Here is the schematic for the 04 GTO charging system. The white wire connects by fusible link directly to the battery. The brown wire should splice into the blue wire on the porsche harness, for switched power and the idiot light circuit. You could run the white wire straight to the B+ post on the alternator but I think there is a reason the factory runs it back to the battery.

That is how mine is wired. Works well.

Worked for me as well!

for those searching about corvette LS6 - it has a 4 wire and so different than fbody AND GTO
1) main charging wire to battery/or starter terminal
2) term "d" at the alt. is red wire w/fusible link to starter
3) term "c" at the alt is gray wire is generator field duty cycle signal to the PCM term c2 52
4) term "b" at the alt is red wire is generator turn on signal to PCM term c2 15

This info all came from ALL DATA wiring schematics.
What does this mean as far as hookup, with idoit light and gauge working properly?
I dont know still figureing this out...suggestions?

some good info (its probably already linked but) here:
http://ls1tech.com/forums/conversions-hybrids/40815-factory-camaro-alternator-question.html

AND

http://ls1tech.com/forums/conversions-hybrids/779728-thee-alternator-faq-thread.html