I have searched by haven't really found a definitive answer.
I have a 2001 5.3 in a 92 fullsize. Truck wiring harness.
The alternator has two wires coming from a weather pak connector.
One is gray, one is brown, and the brown wire has 9.5volts when the key is on,
I assume it is supposed to have 12V.
I am trying to wire in my idiot light to the dash, but am unsure where to splice in.
It appears that the brown wire goes in red 15 on the pcm and a gray wire comes out red 52 as generator field terminal.
I have read that it is important that the light be connected for its resistance.

I have the alternator wire from the original truck dash, but need to know where to hook it in the new harness.

Thanks for any help

 

In your case the light does not need to be hooked up. The only swap that needs the light hooked up is if a 98 PCM is used or if you are not running a PCM.

The 1999 and newer trucks already have the alternator hooked up via the PCM, there is no other wiring that is needed.

The best thing to do is just to leave your old charge wire disconnected, the alternator will function correctly, and the light will always stay off.

 

That is what I wanted to hear.

Thanks for the help

 

pnhigg, since you got your answer, let me barge in for a sec.

I'm putting a carb'ed MSD-6010 powered '03 Corvette LS-1 in a '72 Maverick (no engine harness needed). I thought I had this "alt light" thing figured out, but I'm using an LED in my dash for my alt light. Which *probably* change things a bit since it doesn't provide resistance the way an incandescent bulb does.

Disregarding any factory harness issues, how would I wire up this alternator with an LED indicator?

Thanks!

Russ

 

Did you mean to say " an 03 Corvette LS6 " in your Maverick? The Corvette uses a different alternator than the LS1. Which belt and accessory system are you using?

 

You cannot use an led. It has to be a regular light bulb. I don't think the led has enough resistance.

 

Hmm, I guess...it did have an LS-6 intake on it but I thought all engines after 2003 or so had the LS-6 intake? Anyways, it's a bone-stock 2003 base Corvette 350HP motor with completely stock front drive.

I'm pretty sure an LED can be used, maybe with another resistor in line with it? The purpose of the bulb is to drop the voltage to certain point so the alternator doesn't see the whole 12-14V. These particular LED's already have a built-in resistor (of some unknown Ohm reading) that allows it to be wired into a 12V system without being destroyed.

Any ideas?

Russ

 

I'm not 100% sure what alternator I have, it's from a 2003 Corvette LS-1 base motor (350HP). I have a custom dash with an LED for a charge lamp.

Bench checked some things today, totally inconclusive. This alt has 4 pins, S, F. L, & P. I'm trying to wire this up (carb'ed, no computer) using the diagram on S& P's website. I'm spinning it with a 7" side grinder's rubber backing pad, so it's prolly running around 4000 max. No matter what wires are hooked up, the alt does not begin charging until it's really spinning up, at least 50% speed or better. The charging does not begin until this speed is reached no matter what. Wires connected or disconnected makes no difference. Incandescent bulb or LED, makes no difference. Oddly, with an LED charge lamp the bulb is lit from the start and never goes out, the incand. bulb never lights off (and yes, it's a good bulb). Any or all ideas welcomed!

Thanks!

Russ

 

I guess what I'm seeing is the exciter(?) circuit seems to be inoperable (or at least not what I'm expecting). I tried hooking up 12V to the "L" term and it still doesn't begin to charge until 2000+ RPM's. I can leave off all pigtail wiring and see the same effect...

Russ

 

I have the same problem here also with my LS6 alternator. The dash bulb stays on no matter what resistor I use or how low I drop the voltage. The alternator charges at 14 volts all of the time no matter what I do. I bought it "new" off of E Scam and assume it has a defect in the internal components. Mac

 

Mac, I don't think we're gonna get an answer here...

Russ

 

If you think your alternator is bad take it to autozone and have them test it for free.
No sense quessing on these things.

 

The alternator is NOT bad, it charges 14.2V. Just have to spin it up quite a bit before it starts charging, meaning the exciter circuit is not functioning as expected. This computer-controlled alternator is not doing what's expected and nobody can say why or how to wire it so it does as expected ? ? ? I just want it do as an old-style alternator should, as I do not have a ECM/PCM.

Russ

 

I hope I don't have this problem as well. I have a 98 PCM, BUT, I am using an aftermarket 1 wire alternator that came with my Synister drive kit.......hmmmmmmmm.

 

Forget the fact it ever had a PCM hooked up to it and treat it like a plain old alternator. Computers don't do **** to alternators that just straight wires won't do.

If you hook switched 12V to the excitation wire and it still has to spin 4000 RPM to self excite, then there is probably something wrong with the exciter wiring inside the alternator.

 

That's wht I'm concerned about, is there any way to test for it w/o buying a new alt? Is it something Advance can check out?

Oh, "switched"... Hmmm, for bench testing, I didn't use a switch, just direct hookup to the batt +. Is that a problem (for bench testing only)?

Russ

 

The exciter wire needs to be switched or else it will drain the battery when the car is off. For Bench testing it won't matter.

If I remember right the Autozone tester doesn't spin the alternators overly fast. Maybe they will tell you if it is bad or not.