Carbureted LSX forum - How to wire up Alternator

I need to know, 09 LS2 out of trailblazer SS if that helps.

Thanks

i asked the same question a few weeks ago but about an 07. just run the heavy 12 lead to the main lug on the back and your done.

So its pretty much a 1 wire

exactly. the other wires off the 2 pin connector go to the pcm, which we dont have. it charges fine without them.

Sweet thanks for the info!

no problem (tips hat)

09 Trailblazer doesn't have an excitor wire?

Have to double check mibe when I get home but, pretty sure ya put 470 ohm on brown wire and run to switched ign. Other wire leave hanging.

Did some more poking around and it appears the 2 pin late model alternators don't need anything connected to either of the pins to charge. Very interesting...

it does charge, but not as well as i hoped. my car is very basic and doesnt have alot of amp load...all grounds are actually probably more than needed and it seems to drop off voltage alot with not all that much load. seems almost like there is no feedback to the alt to tell it to ramp up then a load is present.

09 Trailblazer doesn't have an excitor wire?

This one does, it might be an 08 tho. It has the conecter and the power stud.

its a 2 pin connector not a 4. the consensous was wire it like a single wire when i posted this question. i think mine is in the conversions and hybrids section.

Found it here: http://ls1tech.com/forums/conversions-hybrids/1538120-wiring-2007-up-alternator.html

Found the answers interesting. Some saying don't wire it and they run it that way just fine. Others saying wire it. Then someone says you can't wire it the same as you would a 4 pin. Bumped that thread up to see if we can get more answers.

problem is, i dont think anyone knows for sure lol. ive been driving my car around for about a month with it set up single wire and it works, just not as well as i had hoped.

Well if it works it works lol

Like i said though,it doesnt seem to ramp up under load.

What does it do under WOT? Does the voltage drop as the RPM increases?

not that i have noticed...

but if you turn on say...the turn signals,headlights and blower motor it drops hard and stays down. never dropped much with the old cs120 alt in it.

Is that just at idle or at all speeds? If at idle, sounds like it's not spinning fast enough. If at speed, you might have a bad ground or something causing a lot of resistance. Sounds like the alternator itself is working fine.

at any speed. and no way there is a bad ground. i just built the whole car over a month ago...there is 0 gauge grounds everywhere lol

Do yourself a favor and hook the voltage sensing wire up to the alternator. You running an unregulated alternator. Your volts are probably dropping to 8 volts when the blower motor"drops hard".

never gets that low...but close to 12 on my gauge and multimeter. which is the voltage sensing wire? does it need a resistor? (this is basically my origional question that has had no clear answer)

never gets that low...but close to 12 on my gauge and multimeter. which is the voltage sensing wire? does it need a resistor? (this is basically my origional question that has had no clear answer)

In the other thread there was this answer, Gray is the Field Duty Signal so that needs 12 volts (Ign on).

Brown is for one side of the Idiot light. 12 Volts (Ign on) the other side of the light. Otherwise a 470 ohm resistor between this wire and 12 volts (Ign on).

But I think he was talking about the 4 pin.

maybe we should just swap out to the older 4 pin style since no one seems to know for sure? i'd rather not do it wrong and smoke the alt...and maybe my car lol

In the other thread there was this answer,

But I think he was talking about the 4 pin.Lol looky there what I said on page one....:zzz: and no it is for 2 pin

Basically you need the voltage sensing wire so the alt will regulate the voltage.

maybe we should just swap out to the older 4 pin style since no one seems to know for sure? i'd rather not do it wrong and smoke the alt...and maybe my car loljust go to radio shack and buy some 470 ohm resistors and wire it to brown wire and then to switched 12v ;)

there is no brown wire. a red and a grey...now what do i do? lol

there is no brown wire. a red and a grey...now what do i do? lolred then ;)

Because Gray is the Field Duty Signal so that needs 12 volts (Ign on). Since you don't need the gray at all with carb setup, do the red with the resistor to 12v ign.

I did red with resistor grey without both to switched 12v. Seems about the same charging wise. Whatever i guess it will do untill it breaks lol

I did red with resistor grey without both to switched 12v. Seems about the same charging wise. Whatever i guess it will do untill it breaks lolDont need the gray at all for carb setup so...Im assuming you had alt checked out to make sure it is working properly?

Is the idiot light enough of a resistor to just connect the OEM excite wire to new style alternator?
I was using a resistor w/ switched 12v, but I'd like the idiot light to work

dad put 5000 miles on his car with AC never had to charge the battery all summer.

We just have the 1 wire hooked to the battery.

I have EFI on the car now I need to hook the lap top up and look at the voltage but I drove the car all weekend didn't seem to be loosing any ability to start the car.

Tim