Ls alt wiring

[clinebarger]

Originally Posted by ls1nova71

According to that table, 13.8 is 60%???

So is 100%
"When there is loss of class 2 communication with the powertrain control module (PCM), the module will send 100% duty cycle, 13.8 volts"
"Between 0-5 percent and 100 percent are for diagnostic purposes"
"the generator battery control module is limited between 36-90%"

[Daaaanz67]

Sorry for the late response. My truck is not on the road yet but hopefully by the end of this month or early part of next month. I will try to give full report as soon as I can. Yes I used 2004 because lt1swap said the pinouts are similar for 2003-2007 with blue green connector. Also 2006 may have fewer wires. This I found true as I started to strip my harness of unneeded wires. My computer was not flashed for this. Might have to look into the flash later when the truck is on the road. Doesn't the gbcm also get information from the bcm so it can control the field duty cycle?
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[y5mgisi]

Interesting thread.

[chevydog66]

And this is why I just sent my computer and harness to Speartech to get modified and rewired per my application. Definatly interesting thread though.

[awhite4557]

I also used speartech, plugged it in and it has worked like a charm every since. Definately worth the money.

[chevyman70]

I am doing a similar build. My alternator has two wires coming out, gray and brown. They are going to the pcm. So I guess I have the same question, where do I attach my (70 truck brown wire) so that I can use the original gauge? I was thinking of splicing into the alt's brown wire. Any ideas?

[clinebarger]

Originally Posted by chevyman70

I am doing a similar build. My alternator has two wires coming out, gray and brown. They are going to the pcm. So I guess I have the same question, where do I attach my (70 truck brown wire) so that I can use the original gauge? I was thinking of splicing into the alt's brown wire. Any ideas?

A '70 pick-up has a ammeter, If it worked before, It will work when your done. Leave the "LS" alternator regulator wiring alone.

[chevyman70]

Originally Posted by clinebarger

A '70 pick-up has a ammeter, If it worked before, It will work when your done. Leave the "LS" alternator regulator wiring alone.

It did work before I did this swap. Alright, I'll leave it alone. Hopefully it works. I haven't fired it up yet.
Thanks!

[JNJchev77]

Old thread, but didn't want to start a new one...

I want to make sure I have this right, or it's ok to run mine this way...

5.3 LS swap

I want to have a distribution block, with battery in. Then the other three ports will have starter, alternator, and then an open port for now. 4ga wire all around

This safe/ok?

[chevydog66]

Originally Posted by JNJchev77

Old thread, but didn't want to start a new one...

I want to make sure I have this right, or it's ok to run mine this way...

5.3 LS swap

I want to have a distribution block, with battery in. Then the other three ports will have starter, alternator, and then an open port for now. 4ga wire all around

This safe/ok?

You should be fine running it like that. I would still put a fusible link in the output of the alternator, though.

[JNJchev77]

Thanks Chevydog!

[Roostboy102]

I've been searching and reading for the last hour and can't really find a clear answer! What happens with the original three alt wires when doing an ls swap? Theyre not used? I'm having wiring problems (voltage reg making noises, truck goes dead...) but I have 2 of the old alt wires hooked to positive off the alt. I'm just so confused and can't find an answer!!!

With the new style alt how does the truck get power to operate lights and things? If I understand correctly I don't need a voltage reg anymore?

Appreciate any help guys

[ls1nova71]

You don't need your old voltage regulator or the wires going to it. The lights and stuff get power from the small junction block mounted on the fender by the battery, the red wire going to the big plug on the firewall (that the fuse box plugs into), that wire splits off and one part went to the voltage regulator. Just remove it, your alternator will be controlled by the PCM.

[Roostboy102]

Ok so it is just that simple. I was reading like resistors and dummy lights and splicing wires off the regulator... And I was just confused! Thank you!
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[ls1nova71]

Originally Posted by Roostboy102

Ok so it is just that simple. I was reading like resistors and dummy lights and splicing wires off the regulator... And I was just confused! Thank you!
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You only need the resistors if you're going carbureted and don't have a PCM.
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[Roostboy102]

Ok thanks!
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[solidaxel]

Following this future hook ups

[themb2g]

So i have an single wire alternator on an 07 LQ4 with a 2002 wiring harness and PCM. The red goes to the battery, the black grounds to the engine. Where do I hook in the brown wire from the gauge cluster? if there is soemthign that goes back to the PCM, where does it plug into?

here is a pic of the alternator

[ls1nova71]

Originally Posted by themb2g

So i have an single wire alternator on an 07 LQ4 with a 2002 wiring harness and PCM. The red goes to the battery, the black grounds to the engine. Where do I hook in the brown wire from the gauge cluster? if there is soemthign that goes back to the PCM, where does it plug into?

here is a pic of the alternator

You have an old "one wire" alternator, they're self exciting and don't have any other wires. You should be fine with just the battery wire. Personally I don't like them, but they became popular since they're cleaner looking with out the field wires. You generally have to rev the engine a certain ammount to get the alternator to kick on, but isn't really that big of a deal.
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[themb2g]

Thanks for that info. Im still wondering where the brown wire to the cluster gauge goes now as well as do i have to hook anything up to the pcm?

[chevydog66]

Brown goes to generator lamp.
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[Daaaanz67]

I don't think you can use that ammeter as a voltage guage. It's been explained before in another thread actually by ls1 nova maybe it was this thread since I started it. I'm not using my ammeter.
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[chevydog66]

Originally Posted by Daaaanz67

I don't think you can use that ammeter as a voltage guage. It's been explained before in another thread actually by ls1 nova maybe it was this thread since I started it. I'm not using my ammeter.
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True. But originally the brown wire went to the generator lamp.

[themb2g]

so the brown wire goes no where in my case?

[chevydog66]

Right. Don't even need to hook it up. Just run a volt meter.