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ls1 powered z car destroying alternators?


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So here the problem. I have killed 3 alternators in less then a year on the ls1 z car. Cant seem to find an issue.

 

This latest alternator lasted less then a month. Is there anything I should test for? There isn't much that can go wrong on the ls alternator. It grounds to the motor thorough the block. Exciter wire is plugged in fine. The wire from the back goes to the battery. Did a quick test. If i unplug the battery and test the wire its not live when car is running (should be), But when its on the battery it lights up (should be, this shows there are no breaks in the wires). So im running out of ideas.

 

I dont want to keep changing the alternator. I have run out of ideas. Have any of the lsx guys ran into these problems? I know that with the jci mounts you need to "trim" the plastic shroud looking thing to clear the motor mount, so i did that. It does leave the back exposed. Not quite sure if that would cause an issue, but who knows?

 

Talk to me people.

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I have searched on LS1 tech, and talked to a rep at Street & Performance. I am wiring my car now, and wanted to get this straight. 1. What alternator do you have ? CS130, CS130D or CS130AD ? If I am reading correctly, you do not have a pigtail coming off the LS1 harness connected to the alternator? Utilizing the Alt excitor wire may be your problem.

 

Go to the bottom of the page of this Nova Install - If you have the Camaro/TA alternator pictured the pigtail pictured is possibly what you may need?

http://www.hotrodlane.cc/PDFFILES/63%20NOVA.pdf

Give Street and Performance a call.

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So here the problem. I have killed 3 alternators in less then a year on the ls1 z car. Cant seem to find an issue.

 

This latest alternator lasted less then a month. Is there anything I should test for? There isn't much that can go wrong on the ls alternator. It grounds to the motor thorough the block. Exciter wire is plugged in fine. The wire from the back goes to the battery. Did a quick test. If i unplug the battery and test the wire its not live when car is running (should be), But when its on the battery it lights up (should be, this shows there are no breaks in the wires). So im running out of ideas.

.

 

Are you pluging the exciter directly to the battery? It's only deisgned to see 5 volts and you must run a resister on the line for the alternator to live.

 

Cary

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I am running an exciter wire from the pcm (harness was reworked my speartech if that matters). However the alternator was untouched. It does look much different then s&p version however. Mine only has one red wire coming off of it (it doesn't go to the battery, it goes into the motor harness then the pcm.) According to the service manual it should only see 4-5 volts. Ill have to check it to make sure.

 

Forgive my ignorance, but how does the starter affect the life of the alternator. The motor spins fast and starts up in about 1-2 seconds. Pretty sure the starter is strong but I could be wrong?

 

Another thing came to mind. How thick is the wire that is ususally run from the back of the alternator to the battery? I wonder if the wire im using isnt thick enough?

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I am running an exciter wire from the pcm (harness was reworked my speartech if that matters). However the alternator was untouched. It does look much different then s&p version however. Mine only has one red wire coming off of it (it doesn't go to the battery, it goes into the motor harness then the pcm.) According to the service manual it should only see 4-5 volts. Ill have to check it to make sure.

 

Forgive my ignorance, but how does the starter affect the life of the alternator. The motor spins fast and starts up in about 1-2 seconds. Pretty sure the starter is strong but I could be wrong?

 

Another thing came to mind. How thick is the wire that is ususally run from the back of the alternator to the battery? I wonder if the wire im using isnt thick enough?

 

 

I had a buddy who is an electrical engineer come over to the house with his equipment and he determined the starter was sending out an AC spike. He said it would kill the alternator. I replaced the starter, it fixed my problem.

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Hmmm. Thats interesting. How did he test for the spike (multimeter? where was the test point)? Maybe I should give this a shot and see if its happening to me (id like to see if i can test for it first though before i spend more money..:()

 

 

I had a buddy who is an electrical engineer come over to the house with his equipment and he determined the starter was sending out an AC spike. He said it would kill the alternator. I replaced the starter, it fixed my problem.
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I have a re-worked harness/PCM from Speartech as well, but my alternator Delphi plug has a gray wire and a red wire. I sold the F-body accessories (AC,PWR steering and the alternator) I picked up a pigtail to adapt to my CS 130 alternator I have now. What alternator do you have ? Because that will determine if you need a resistor or not as tube80z indicated. There is a difference in the connections for pre 2000 GM alternators. Also, look at the letters on your alternator if you can - Is there a S, F, L and P ?

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Ill look for the letters on the alternator and post my findings.

 

However I did some reading. Most people fuse the line going from the back of the alternator (150amp). I didnt. Probably should I guess, opinions? btw I still would like to know if the wire im running is thick enough. What do most people run gauge wise?

 

Ill find the letters on the alternator and post the info I find. Reading suggests that camaro alternators need a resistor in place somewhere. Not sure where. Ill find out what alternator I have and figure it out from there.

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Hmmm. Thats interesting. How did he test for the spike (multimeter? where was the test point)? Maybe I should give this a shot and see if its happening to me (id like to see if i can test for it first though before i spend more money..:()

 

 

It was some type of meter but not a multimeter sorry I can't be more specific.

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There is definitely supposed to be a resistor in-line with the exciter wire. I had a problem recently when I bought a reman' alternator, the thing WOULD NOT charge at all!! It was putting out like .233 volts and sending voltage back through the chassis.. crazy stuff!

 

My Exciter wire had the 12 volt to 500ohm resistor, and was utilizing the #3 prong in the plug I believe..

 

It ended up being that I had to run a straight 12v to the #1 or #2.. cant remember right now... prong and then it charged fine, didn't drain my battery, and didn't backfeed voltage into my chassis anymore. So I actually have 2 wires hooked up to that plug-in. Has something to do with truck alt vs. camaro/vette alt...

 

Hope this helps you! I have heard of a lot of stories about people burning up alternators because they dont have the exciter wires wired up correctly..

 

As a matter of fact, here is a picture to show you how mine works.

 

001.jpg

 

Red wire is the one with the 500 ohm resistor.

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Thing is, I only have one wire coming out of that plug in (red). Alternator charges fine, but the question is for how long before I replace it again.

 

I know there is a prob. So thats kinda why The new alternator is installed but I haven't drove it cause I want to get it right this time.

 

Still wondering how big a wire people normally run, and what size fuse to place on this thing. Still confused whether to put a resistor on the red wire or not. Seems like people who do put a resistor in place have multiple wires coming off the alternator plug in. My harness does not only one exciter red wire (camaro set up).

 

Thanks for the help so far. I think we are on to something.

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I would definitely try to 500 ohm resistor in that 12V wire.

 

What kind of voltage is it putting out? Try at idle AND at 2500 rpm.

 

Most say that if you dont have that exciter wire 500 ohm'd then you will be seeing voltages that are wayyy too high and that WILL kill the alternator. If all else fails either put a prong in the plug you have now and use the 2 I have, or go pick up a tahoe, surburban, truck, whatever plug, and they have 2 wires like mine. I chased problems for a very long time and wiring it up like this fixed everything.

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Thing is, I only have one wire coming out of that plug in (red). Alternator charges fine, but the question is for how long before I replace it again.

 

I know there is a prob. So thats kinda why The new alternator is installed but I haven't drove it cause I want to get it right this time.

 

Still wondering how big a wire people normally run, and what size fuse to place on this thing. Still confused whether to put a resistor on the red wire or not. Seems like people who do put a resistor in place have multiple wires coming off the alternator plug in. My harness does not only one exciter red wire (camaro set up).

 

Thanks for the help so far. I think we are on to something.

aziza z: NEVER assume that you have a good ground on the alternator. Run as big a wire bolted to the case of the alternator as that running to the battery for charging. This is the HIGH amperage charging circuit. Perhaps the later (latest) alternators are supplied with a voltage for excitation other than 12 volts but that would seem STRANGE. If the cable from the battery to the starter and cable from the alternator to the battery are of sufficient heavy gauge, the inductive spikes from the starter should be absorbed by the battery. The type/model of (GM?) alternator still needs to be identified in order to know better what is going on with your situation.

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aziza z: NEVER assume that you have a good ground on the alternator. Run as big a wire bolted to the case of the alternator as that running to the battery for charging. This is the HIGH amperage charging circuit. Perhaps the later (latest) alternators are supplied with a voltage for excitation other than 12 volts but that would seem STRANGE. If the cable from the battery to the starter and cable from the alternator to the battery are of sufficient heavy gauge, the inductive spikes from the starter should be absorbed by the battery. The type/model of (GM?) alternator still needs to be identified in order to know better what is going on with your situation.

 

If the ground wasn't good, wouldn't that mean that the alternator would not charge at all? Exciter wire should not see 12vs. It should be no more than 4 volts (and it does see this). Wire guage is 8ga at this time (but it was unfused at the time). Alternator Part # is dl160715-5.

 

 

I would definitely try to 500 ohm resistor in that 12V wire.

 

What kind of voltage is it putting out? Try at idle AND at 2500 rpm.

 

Most say that if you dont have that exciter wire 500 ohm'd then you will be seeing voltages that are wayyy too high and that WILL kill the alternator. If all else fails either put a prong in the plug you have now and use the 2 I have, or go pick up a tahoe, surburban, truck, whatever plug, and they have 2 wires like mine. I chased problems for a very long time and wiring it up like this fixed everything.

 

 

Ill test the voltage at 2500 and get back to you on that. Btw where does the white wire go on ur plug in?

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  • 2 weeks later...

So heres an update. Havnt been driving the z car because of this issue. I cant afford to destroy another one.

 

I wired in a 100amp fuse (is that big enough?) in line with the wire going from the rear of the alternator. Wire is an 8 gauge. At idle battery is charging around 14.3 That voltage does not move up or down at different rpms. It stays around there. I tried a resistor inline and it does nothing at all. So I uplugged the wire completely "just to see". And the alternator stops charging.

 

Could is be a ground? I dont want to destroy another one. What else should I test?

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