Generation III External Engine LS1 | LS6 | Bolt-Ons | Intakes | Exhaust | Ignition | Accessories
Sponsored by:
Sponsored by:

ls1 Alternator not charging

Thread Tools
 
Search this Thread
 
Old Jan 25, 2011 | 04:28 PM
  #1  
jlee29's Avatar
Thread Starter
On The Tree
iTrader: (5)
 
Joined: Sep 2009
Posts: 120
Likes: 0
From: California
Default ls1 Alternator not charging

I am running an alternator and harness from a 2001 T/A LS1, PCM 99' T/A, in a 240sx (no volt gauge in car)
4 prong- single red wire style (10.2 volts with ign on)

I have tried and tested:
B+ wire is connected and works properly.
Ground is working properly.
Red excite wire L-Terminal gets 10.2v from PCM with Ign on/ also tried 470ohm inline resistor.
Battery is good.
Alternator is brand new and I had it tested 4x and is working properly


The alt will only charge with a wire running directly from the battery to the L-terminal without a resistor ( Will not charge with resistor in line)

From my understanding I can not run a direct 12v to the L-terminal without frying my alt. but that is the ONLY way i can get it to put out a charge.(It put out 14.6~volts directly to 12v)

What can I do? I am at a lose for ideas. What is the exact voltage the red L-terminal wire needs to excite alternator?
Reply
Old Jan 25, 2011 | 08:42 PM
  #2  
jlee29's Avatar
Thread Starter
On The Tree
iTrader: (5)
 
Joined: Sep 2009
Posts: 120
Likes: 0
From: California
Default

Should I just try running it with a straight 12v power source to the L-terminal (Since that is the only way it will charge)
Reply
Old Jan 26, 2011 | 03:30 PM
  #3  
jlee29's Avatar
Thread Starter
On The Tree
iTrader: (5)
 
Joined: Sep 2009
Posts: 120
Likes: 0
From: California
Default

Can someone atleast conform that it is indeed bad to run straight 12v to the L-terminal only?
Reply
Old Jan 26, 2011 | 04:31 PM
  #4  
marc a's Avatar
Staging Lane
15 Year Member
Photogenic
Photoriffic
Liked
iTrader: (1)
 
Joined: Apr 2007
Posts: 83
Likes: 5
From: Sarasota, FL
Default

You might want to try this: http://www.sonicelectronix.com/item_...a-AFDI-5V.html

It is my understanding that the alternator is looking for 5v from the BCM (Body control module), not the PCM. My "exciter" wire is from my in dash volt meter/idiot light that sends 12v to the Alt. My alt was not charging either until I installed this converter. Comes with instructions.

Good luck
Reply
Old Jan 26, 2011 | 04:47 PM
  #5  
jlee29's Avatar
Thread Starter
On The Tree
iTrader: (5)
 
Joined: Sep 2009
Posts: 120
Likes: 0
From: California
Default

Thank you ill give it a try!
Reply
Old Apr 9, 2014 | 06:42 PM
  #6  
lq4240sx's Avatar
Staging Lane
 
Joined: Aug 2010
Posts: 69
Likes: 0
From: NC
Default

Any update on this I'm running into the same issue
Reply
Old Apr 9, 2014 | 09:26 PM
  #7  
LS1MCSS's Avatar
TECH Junkie
iTrader: (18)
 
Joined: Jan 2006
Posts: 3,831
Likes: 8
From: Dover, Arkansas
Default

That post is over three years old.
Reply




All times are GMT -5. The time now is 02:34 AM.

story-0
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-1
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-2
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-3
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-4
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-5
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-6
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-7
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-8
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-9
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE