Thee Alternator FAQ thread

[G-Body]

All of the alternators used on LSx engines have 2 connection points.
1. The main output stud on the back. Connect this to the + battery cable/terminal or to the main power distribution center.

2. The 4 pin weatherpack connector. There are 4 pins, but not all 4 are used in every application. See posts below to determine which one(s) are needed.

If you are hooking up the alternator using the wiring harness and PCM from the same bodystyle vehicle as the alternator the wiring is already done, unless you have a 1998 f-body PCM/harness.

If you are not using the factory harness/pcm or are using a 1998 f-body harness PCM refer to diagrams below.

1998 F-body

1999-2002 F-body

Corvette

Trucks 1999-2000

Trucks 2001-?

Somewhere around 2003 the trucks or at least some of them started using 3 of the 4 wires, but I don`t know if it all of the trucks started this at the same time or if only some models are using 3 wires. If anyone has any wiring diagrams for the 2003 and newer and could post them or send them to me that would be great. I don`t have any info for the GTO`s or the FWD (new monte/impala) yet either.

Heres a link to the resistors http://www.radioshack.com/product/in...tId=2062320&cp

Heres a link to the original alternator thread http://www.ls1tech.com/forums/showthread.php?t=40815

[downtowncb]

Does anyone have the pin diagram for the chevy trucks that use 3 of the 4 connectors as G-Body said? I need to know what pin A does on my connector from a 2003 Silverado, it runs to connector C100 pin J. Thanks

[Jones'n]

What about the 04-up engines with the 2 wire alternator?
and the Corvettes with the 3 wires in the 4 pin connector?

Also.... don't most of the alternator wires go to the computer after 1998? I didn't think there was a need to remove it from the computer and run it to a resistor.

[cooks 7]

I always wondered about this. My setup isn't the normal one, but someone else might have the same question. I am running a Powermaster alternator, it is a one wire hookup, just the big power output wire, it's self exciting. So I didn't use the hookup from the weatherpack at all, is the purpose of the weatherpack wire to excite the stock alt.? I have run the car and it charges and I don't get an SES light so I guess the computer doesn't care that the wire isn't hook up. Any insights? By the way the engine and harness are from a 2001 F body.
Thanks

[poconojoe]

If you run the self-exciting alt you need to turn the codes off in the PCM, so the SES light doesn't come on. The one wire alternator is the best way to go

[G-Body]

downtowncb: The wire in pin A (probably a dk blue wire) is for the supplemental brake assist module. Just eliminate it from the alternator. I``m not really sure exactly what it does (I suspect its there to turn up the alternator output when the SBA module kicks in) but eliminating that wire does not seem to effect normal alternator operation (Thats what I did on my friends swap).

Jones'n: Yes, the 98 f-cars are the only ones that do not go to the PCM. On the 99+ everything else the alternator will work without having to do anything to the wiring (As long as you keep the PCM, but the carb people have to wire it up with a light or resistor).

cooks 7 / poconojoe: The purpose of the wire on the 98-02 f-bodies is to excite the alternator. I don`t know that single wire alternator is better per se, just easier to hook up. I know that on the older (think GEN I SBC era) single wire alternators there were problems with low speed charging. They would not charge until the engine was revved past 2500rpm, and on some, they would not charge at all below 2000-2500rpm. I would hope that those problems would have been resolved with the newer designed alternators though.

[downtowncb]

Thank you very much, that's exactly what I needed to know.

[poconojoe]

G-body
the only issue with the one wire on the first gens is some of the regulators didn't turn on until you rev the motor, when you first started it, this was so the alternator would not try to tuen on, when cranking over. Once turned on, they would keep charging until until you shut off the motor. It was the high output alternators, that would not charge at low RPM's

[cooks 7]

I talked to powermaster when ordering my alt. they said the key to charging at idle and also not over spinning an alt. is pulley selection. they have a writeup on their page about it.

http://www.powermastermotorsports.co...r_pulleys.html

With my Summit underdrive balancer i found it difficult to get the exact ratio i needed though, if i shift too high in the rpms i'll be close to overspinning it. I'd rather take that chance than underpowering it at idle though. seems to excite and charge fine at idle now with their 3 to 1 ratio for the street.

[jannes_z-28]

Very good information G-Body.

This should be a Sticky!


Jan

[G-Body]

A link to this thread is listed in the FAQ sticky in post 13 http://www.ls1tech.com/forums/3859121-post13.html

[Pig Pen]

Is there anything that would keep one from using a cavalier alternator in a swap.

[poconojoe]

I don't think the mounting holes are correct. I know the later model S10 alternators from the 4.3's fit on the the truck mounts

[Pig Pen]

Thanks for the answer. I'm more concerned about it plugging in and functioning properly.