October 22, 2019, 03:48:14 PM

Author Topic: LS6 Alternator no output, exciter ??  (Read 275 times)

Offline rajeevx7

  • Pre-Staging
  • Location: Merritt Island, FL
  • Posts: 120
  • FD owner since 1998. V8FD owner since 2010
  • View Gallery
    • View Profile
LS6 Alternator no output, exciter ??
« on: September 21, 2019, 07:47:02 PM »
Hi Team,

No alt output on my 2002 oem LS6. Please help if you know, it could save me tons of labor! Iím sure I knew these answers 10yrs ago:-)

My built harness is a single wire exciter in a 4 pin plug, what position should that wire be? Is it powered with key on? What voltage?

What do the EGI and Circuit relays control on the FD side? Would they have anything to do with not turning the alt on?


Thanks!
Raj
'93 BB R1 Ls6 - 2001-Current
'93 MB Touring 13b-Rew - 1998-2001



Offline kinger

Re: LS6 Alternator no output, exciter ??
« Reply #1 on: September 21, 2019, 09:32:21 PM »
Hi Raj

The wire should be 12v switched.  It basically tells the voltage regulator to turn on.   Nothing to do with any other circuits. 

I actually have a self exciting regulator which means it turns in when it senses the pulley turning. This eliminates all wires except for the main post.

These alternators were never known for great durability.  The rectifiers are stacked on top of each other and usually the alt fails when it heats up.  Mine is currently doing that. Charges at cold and not once warm (or intermittent) I actually ordered a new one from the alternator man itís a 170 amp vs the stock 105 in the self exciting regulator. 

If you search ls1tech youíll figure out your wire in the plug. 




Sent from my iPhone using Tapatalk
93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Online Cobranut

Re: LS6 Alternator no output, exciter ??
« Reply #2 on: September 22, 2019, 12:16:05 AM »
That wire should come from the CHARGE light in the instrument panel.
One end of the bulb is tied to SW 12v, and the other feeds the alternator.
If the alternator fails, it pulls the line to ground and turns on the bulb.
If you don't use the light, I think it needs a 100ohm or so resistor in line with the lead.
1995 FD, 7.0 Liter stroked LS3, T56, 8.8, Samberg kit.

Offline rajeevx7

  • Pre-Staging
  • Location: Merritt Island, FL
  • Posts: 120
  • FD owner since 1998. V8FD owner since 2010
  • View Gallery
    • View Profile
Re: LS6 Alternator no output, exciter ??
« Reply #3 on: September 22, 2019, 04:13:53 PM »
Hey guys! Thank you for the help and guidance :D  Based on what you said, I tested the exciter and it was 10.5ish with key on and it was pinned to the right spot. That self exciting alt should be the way of the future in everything! And I didnít mess with the two Mazda relays. Iíve ordered an alt that seemed to be the best bang-4-buck. Eta is about 2wks so I have plenty of time to wrestle the old one out. Thanks again :cheers:


Been about a decade since Iíve had to wrench on this car at all...but it also cost me a track day at hot August heat Daytona when it died after one lap  :drive:
'93 BB R1 Ls6 - 2001-Current
'93 MB Touring 13b-Rew - 1998-2001



Offline rajeevx7

  • Pre-Staging
  • Location: Merritt Island, FL
  • Posts: 120
  • FD owner since 1998. V8FD owner since 2010
  • View Gallery
    • View Profile
Re: LS6 Alternator no output, exciter ??
« Reply #4 on: September 22, 2019, 04:14:15 PM »


180 amp in a factory cs130d case $120 shipped
'93 BB R1 Ls6 - 2001-Current
'93 MB Touring 13b-Rew - 1998-2001



Offline kinger

Re: LS6 Alternator no output, exciter ??
« Reply #5 on: September 22, 2019, 08:00:37 PM »
Let me know how it works out.  I read a lot about units lasting 6 months so I went for some Mercia built unit with high quality diodes.  It was $249.


Sent from my iPhone using Tapatalk
93 Touring, 6.3L, T56 Magnum, Mamo RPS BC2 clutch, FAST 90, NW 90TB TB, 8.8, samberg everything, AC, PS, TC, Cruise, LED Tails, HID head lights

Offline rajeevx7

  • Pre-Staging
  • Location: Merritt Island, FL
  • Posts: 120
  • FD owner since 1998. V8FD owner since 2010
  • View Gallery
    • View Profile
Re: LS6 Alternator no output, exciter ??
« Reply #6 on: September 28, 2019, 02:05:40 PM »
Output is 14.7-15.8 at idle. My underdrive pulley was re-used, so actual amperage is unknown. Hopefully the thing lasts a while, if it doesnít Iíll let you guys know. Years of charging up deeply discharged lead acid batts probably cooked the little guy that had an alleged 80k miles on it from the donor car. The exciter wire plugs into the ĎLí port on the alt which is the second pin from the drivers side. I also used the oem GM heat guide snapped onto the back of the alt.

Install could have been easier if I had originally only used 2 bolts (top and rear). I had to disconnect the upper rad hose, and shift the fan shrouds up to remove that lower front bolt. It did NOT go back in on assembly, and everything seems solid with just two bolts. The alt must be loosened, rested on the anti-sway bar and then the alt bracket removed. This gives enough clearance to swap alts from behind my factory-ish mount radiator. Iíd assume there would be JUST barely enough room to squeeze the larger cased 200+amp alts in there, as this was semi-tight but not full-squeeze tight.

Shiniest thing in the bay now ::)  :cheers: to another 10yrs of not having to wrench on this car!
« Last Edit: September 28, 2019, 02:22:19 PM by rajeevx7 »
'93 BB R1 Ls6 - 2001-Current
'93 MB Touring 13b-Rew - 1998-2001



Offline rajeevx7

  • Pre-Staging
  • Location: Merritt Island, FL
  • Posts: 120
  • FD owner since 1998. V8FD owner since 2010
  • View Gallery
    • View Profile
Re: LS6 Alternator no output, exciter ??
« Reply #7 on: September 28, 2019, 02:27:13 PM »
 :)
'93 BB R1 Ls6 - 2001-Current
'93 MB Touring 13b-Rew - 1998-2001