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Alternator wiring

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I have a 2005-2006 GTO Alternator on my LS3 which has a two pin plug. The 2 plugs run to the stock ECU which i guess would turn it on when needed.

The two wires are labelled as follows in the wiring pinout -

Generator Field Duty Cycle Signal

Generator Turn On Signal

Now I have a Link G4+ Xtreme, how do i get my alternator running and charging?

Morning Alex :-).

Had a quick google, post 11 of this thread: https://ls1tech.com/forums/conversions-hybrids/1333228-2-wire-truck-alternator-wiring.html is really helpful.

Looks like you can just supply the generator turn on signal, and the regulator inside the alternator will detect a field control circuit failure, and default to an output voltage of 13.8V. This will be measured at the main output stud, so you'll have to make sure your main charging wire is in good condition.

With a bit of mucking around, I reckon you could get one of the PWM capable aux outputs of the G4+ to correctly command the alternator output voltage though. Would have to figure out what sort of signal it wants though, but I'd suspect it'd be 0-5V, 128Hz.

Hi Zac,

Thanks for the link. I had seen that, but as the wires are different colours, i disregarded it. I think i have been thinking to much into this, its just an alternator!

I wired the generator on to a 12v switched ignition and it started charging as expected, i am still on a very basic base tune when i did this and the idle started fluctuating a little. I had been making changes to the tune the last few days until i realised the battery was draining quite quickly (has been on trickle charge mostly, only noticed when running with it off). Could this be because the battery was draining and it was moving the injector voltage slowly downwards with the voltage drop so it was adjusting the fueling, now it has the correct volts, things are working properly and it needs adjusting again? I think it did level out a little but i didnt have the wire hooked up to long as i read that i could potentially damage it sending a 12v signal to it.

I will give your suggestion a try with the PWM output, as long as its getting a signal, and 5v i think it should come on :)

i can tell that just giving 12v to the generator circuit wont be enough. You can do that on the earlier vx-vy ls1 alternators as they have a built in regulator. the gto which got the later vz style alternator requires the pwm to charge properly.

I did what Zac suggested and it's charging at 14.4v

You should still try and get the PWM control working, because, you know, it'd be cool :-).

Yeah i did, thats how i got it working :)

Sweet! Can you control the output voltage?