Ls alt wiring - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

clinebarger · 05-07-2012, 10:46 PM

Quote:

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 · 05-08-2012, 11:50 PM

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?
Posted via Mobile Device

y5mgisi · 05-09-2012, 12:36 AM

Interesting thread.

chevydog66 · 05-29-2012, 09:09 PM

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 · 05-30-2012, 12:57 AM

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

chevyman70 · 06-25-2012, 01:27 AM

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 · 06-25-2012, 07:42 PM

Quote:

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 · 06-25-2012, 07:50 PM

Quote:

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 · 05-07-2013, 05:59 PM

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 · 05-08-2013, 10:30 PM

Quote:

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 · 05-09-2013, 12:23 AM

Thanks Chevydog!

Roostboy102 · 06-20-2013, 11:49 PM

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 · 06-21-2013, 12:11 AM

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 · 06-21-2013, 06:22 AM

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!
Posted via Mobile Device

ls1nova71 · 06-21-2013, 09:23 AM

Quote:

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!
Posted via Mobile Device

You only need the resistors if you're going carbureted and don't have a PCM.
Posted via Mobile Device

Roostboy102 · 06-22-2013, 06:55 AM

Ok thanks!
Posted via Mobile Device

solidaxel · 06-22-2013, 11:25 PM

Following this future hook ups

themb2g · 06-23-2013, 11:17 AM

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 · 06-23-2013, 01:19 PM

Quote:

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.
Posted via Mobile Device

themb2g · 06-23-2013, 04:34 PM

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 · 06-23-2013, 06:37 PM

Brown goes to generator lamp.
Posted via Mobile Device

Daaaanz67 · 06-23-2013, 09:26 PM

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.
Posted via Mobile Device

chevydog66 · 06-23-2013, 10:06 PM

Quote:

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.
Posted via Mobile Device

True. But originally the brown wire went to the generator lamp.

themb2g · 06-23-2013, 10:53 PM

so the brown wire goes no where in my case?

chevydog66 · 06-23-2013, 10:58 PM

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

05-08-2012, 11:50 PM	#27
Daaaanz67 Registered User Join Date: Nov 2011 Location: Idaho Posts: 857	Re: Ls alt wiring 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? Posted via Mobile Device

05-09-2012, 12:36 AM	#28
y5mgisi Second Chance Program Join Date: Jun 2006 Location: Portland, OR Posts: 2,642	Re: Ls alt wiring Interesting thread.

05-29-2012, 09:09 PM	#29
chevydog66 GM ONLY BABY!!! Join Date: Oct 2003 Location: Fort Wayne, IN. Posts: 1,998	Re: Ls alt wiring 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. __________________ 2 wrongs don't make a right, but 3 lefts do. 66 Chevelle Malibu 406ci, 573hp, 10.99@121mph 96 Chevy Silverado Z71 72 GMC 1500 Super Custom LS 6.0/4L65 on airride http://www.cardomain.com/ride/707879...mc-c-k-pick-up

05-30-2012, 12:57 AM	#30
awhite4557 Registered User Join Date: Dec 2007 Location: Odessa, Texas Posts: 212	Re: Ls alt wiring I also used speartech, plugged it in and it has worked like a charm every since. Definately worth the money. __________________ 1950 Chevy 3100 Ramp Bed 1-ton http://67-72chevytrucks.com/vboard/s...d.php?t=749386 1965 Chevy Step Side 1971 Chevy Short Wide Bed http://67-72chevytrucks.com/vboard/s...d.php?t=277191 1971 Chevy C-30 1-ton 1971 Chevy Chevelle 1972 Chevrolet C-30 1 ton 2005 Dodge Ram 2500 5.9 Cummins 2017 Fleetwood Pace Arrow 35M motorhome 350 Cummins 2020 Jeep Wrangler Unlimited Rubicon

06-25-2012, 01:27 AM	#31
chevyman70 Registered User Join Date: May 2002 Location: Lakewood, CA Posts: 194	Re: Ls alt wiring 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?

05-07-2013, 05:59 PM	#34
JNJchev77 Registered Cruiser Join Date: Mar 2010 Location: Mesa, AZ Posts: 918	Re: Ls alt wiring 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? __________________ 77' Chevy SB Dropmembered Front and Rear 5.3/4l60e combo

05-09-2013, 12:23 AM	#36
JNJchev77 Registered Cruiser Join Date: Mar 2010 Location: Mesa, AZ Posts: 918	Re: Ls alt wiring Thanks Chevydog! __________________ 77' Chevy SB Dropmembered Front and Rear 5.3/4l60e combo

06-20-2013, 11:49 PM	#37
Roostboy102 Registered User Join Date: Jan 2012 Location: Amish Country Posts: 138	Re: Ls alt wiring 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 __________________ 72 C10 - Multicolor, 4.8 ls, NV3500. Sold 72 K5 - Under Construction

06-21-2013, 12:11 AM	#38
ls1nova71 Registered User Join Date: Dec 2009 Location: Independence Mo Posts: 4,119	Re: Ls alt wiring 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. __________________ My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html

06-21-2013, 06:22 AM	#39
Roostboy102 Registered User Join Date: Jan 2012 Location: Amish Country Posts: 138	Re: Ls alt wiring 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! Posted via Mobile Device __________________ 72 C10 - Multicolor, 4.8 ls, NV3500. Sold 72 K5 - Under Construction

06-22-2013, 06:55 AM	#41
Roostboy102 Registered User Join Date: Jan 2012 Location: Amish Country Posts: 138	Re: Ls alt wiring Ok thanks! Posted via Mobile Device __________________ 72 C10 - Multicolor, 4.8 ls, NV3500. Sold 72 K5 - Under Construction

06-22-2013, 11:25 PM	#42
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: Ls alt wiring Following this future hook ups __________________ 53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42

06-23-2013, 11:17 AM	#43
themb2g Registered User Join Date: Jul 2010 Location: Portland, Oregon Posts: 411	Re: Ls alt wiring 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 __________________ Check out my build: 1972 LQ4 Swap http://67-72chevytrucks.com/vboard/s...=1#post5427693

06-23-2013, 04:34 PM	#45
themb2g Registered User Join Date: Jul 2010 Location: Portland, Oregon Posts: 411	Re: Ls alt wiring 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? __________________ Check out my build: 1972 LQ4 Swap http://67-72chevytrucks.com/vboard/s...=1#post5427693

06-23-2013, 06:37 PM	#46
chevydog66 GM ONLY BABY!!! Join Date: Oct 2003 Location: Fort Wayne, IN. Posts: 1,998	Re: Ls alt wiring Brown goes to generator lamp. Posted via Mobile Device __________________ 2 wrongs don't make a right, but 3 lefts do. 66 Chevelle Malibu 406ci, 573hp, 10.99@121mph 96 Chevy Silverado Z71 72 GMC 1500 Super Custom LS 6.0/4L65 on airride http://www.cardomain.com/ride/707879...mc-c-k-pick-up



Register or Log In To remove these advertisements.

06-23-2013, 09:26 PM	#47
Daaaanz67 Registered User Join Date: Nov 2011 Location: Idaho Posts: 857	Re: Ls alt wiring 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. Posted via Mobile Device

06-23-2013, 10:53 PM	#49
themb2g Registered User Join Date: Jul 2010 Location: Portland, Oregon Posts: 411	Re: Ls alt wiring so the brown wire goes no where in my case? __________________ Check out my build: 1972 LQ4 Swap http://67-72chevytrucks.com/vboard/s...=1#post5427693

06-23-2013, 10:58 PM	#50
chevydog66 GM ONLY BABY!!! Join Date: Oct 2003 Location: Fort Wayne, IN. Posts: 1,998	Re: Ls alt wiring Right. Don't even need to hook it up. Just run a volt meter. __________________ 2 wrongs don't make a right, but 3 lefts do. 66 Chevelle Malibu 406ci, 573hp, 10.99@121mph 96 Chevy Silverado Z71 72 GMC 1500 Super Custom LS 6.0/4L65 on airride http://www.cardomain.com/ride/707879...mc-c-k-pick-up

Register or Log In To remove these advertisements.