The fix for my endless alternator failure's
Have you noticed any better gas mileage? I swear I read a thread a long time ago where a board member got some high output alternator from ebay and he claimed that he found another 1-3 mpg... or something like that. As I recall others jumped on board saying that they'd also seen better MPGs out of bigger alternator. I hope this doesn't sound like a stupid hydrogen-injection flux-capacitor type of question, lol.
Unfortunately I wont be able to tell you, I made a bunch of changes at the same time I did the alternator. I took the car down for a week and replaced the fuel pump, swapped torque converters from a basically 2500 stall (it was a yank PY3400, made for 800+HP cars so I couldn't stall it up) to a SS3800 which stalls much higher, and I also changed the tune. So I will have to leave it to one of these other guys.
I have put some mileage on it but I haven't been driving the car in the same exact situations the last couple weeks that I normally do, I had to take a long trip and had a loaner lexus last week so im halfway through a tank of gas that consists of normal driving, so once its on E this tank I will have something to compare too.
Guys I highly recommend this "mod" it is working phenomenal for me, now I just need to run a second wire along the wire from the alternator to the battery to help carry the increased amperage. The stock wire was not installed with the intention to be mated up with a 145 amp alternator.
I'd imagine that if you get a junkyard LQ9 that it would most likely have that alternator on it, especially if you got it out of an escallade. If I go that route then I'll most likely reuse the 6.0 alternator. Thanks for the info! 
I like your thinking, just go ahead and buy the whole damn 6.0 instead of a piece at a time
Although I dont know if the 105 amp from the trucks works, I used the 145 amp and it does, but I would imagine the 105 probably mounts all the same. But would be less benefit because the F body is a 105 too.
I been through 7 alternators through the dealer in 3 months. I got the car back today after GM recommended doing the BIG 3 upgrade (I told them what it was) and the volts slowly started going down in a 10 mile drive. I floored it, shifted, and it blew again.
If you have been through that may alternators, there has to be something else on the car causing them to blow, like faulty wiring.
TECH Junkie
Joined: Dec 2005
Posts: 3,092
Likes: 11
The aluminum bracket that holds the truck alternator on the trucks may be of a different design that does not require the rear support brace like what is used on the Camaro and Firebirds. I know in the third gens if you leave off the rear support brace you will sooner or later break the aluminum bracket that supports the alternator. Just something to think about.
I upgraded to the BIG 3 using Innovative Wiring kit and replaced the exciter wire all the way back to the pcm to include the connector. WOT kills them everytime.
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Brett Foote The aluminum bracket that holds the truck alternator on the trucks may be of a different design that does not require the rear support brace like what is used on the Camaro and Firebirds. I know in the third gens if you leave off the rear support brace you will sooner or later break the aluminum bracket that supports the alternator. Just something to think about.
I have heard of that too, how many RPM's you turn? My limiter is set at 6700, so far this truck one is holding it just fine. If you think RPM's are killing it, which if you turn well over 7000 its a possibility, they make pulleys to slow down the alternator for pretty cheap. I saw them at either Texas Speed or Thunder Racing's website.
Maybe I'm just getting a series of bad delco remans. They put one new delco on and it lasted until it got caked in mud from going to the nascar race in texas. Wife didn't tell me the parking lot wasn't paved which made me extremely happy and that much more excited to go.
Also, I have a huge red top optima battery that's been in the car since all the alternators have been replaced. It tested good but maybe not under a load?
Also, I have a huge red top optima battery that's been in the car since all the alternators have been replaced. It tested good but maybe not under a load?
GM finally got with me on my alternator issue. Service adviser called and said the pcm harness had alot of corroded wires and moisture in it and would need to be replaced. I then told her, the dealership already replaced the pcm Jan 09 so she looks through my records and said ok I'll talk to my manager and call you back. She said they replaced the pcm but not the harness and we can't keep fixing your car for free. I said just last week you printed me out a service diagnosis stating all wiring and electrical components are in correct working order. They even did their "Goodwrench Inspection" and pulled my plugs, wires, and checked my air filter without telling me until I seen it on my sheet. I guess they were looking for lean or rich conditions which were not found.Needless to say, I'm going to pick my car up.
I had my car tuned a few months ago and it had no problems with reading the computer. I also have no other issues with the car like misfiring, codes, or running bad. It just keeps blowing alternators and the entire exciter wire with plug was already replaced.
I had my car tuned a few months ago and it had no problems with reading the computer. I also have no other issues with the car like misfiring, codes, or running bad. It just keeps blowing alternators and the entire exciter wire with plug was already replaced.
GM finally got with me on my alternator issue. Service adviser called and said the pcm harness had alot of corroded wires and moisture in it and would need to be replaced. I then told her, the dealership already replaced the pcm Jan 09 so she looks through my records and said ok I'll talk to my manager and call you back. She said they replaced the pcm but not the harness and we can't keep fixing your car for free. I said just last week you printed me out a service diagnosis stating all wiring and electrical components are in correct working order. They even did their "Goodwrench Inspection" and pulled my plugs, wires, and checked my air filter without telling me until I seen it on my sheet. I guess they were looking for lean or rich conditions which were not found.Needless to say, I'm going to pick my car up.
I had my car tuned a few months ago and it had no problems with reading the computer. I also have no other issues with the car like misfiring, codes, or running bad. It just keeps blowing alternators and the entire exciter wire with plug was already replaced.
I had my car tuned a few months ago and it had no problems with reading the computer. I also have no other issues with the car like misfiring, codes, or running bad. It just keeps blowing alternators and the entire exciter wire with plug was already replaced.
Ask her this, if its bad wiring, why does a new alternator fix the issue every time? I was faced with this garbage when I took my alternator back to get a refund, they would only offer me a replacement part, I told them I have replaced too many of their replacement parts already and I have a 40 dollar alternator on the car right now that works perfect and their 249 dollar alternator wont work right for 30 minutes.
The hotter it got the lower the voltage went, so it worked, cold. So what does the genious at NAPA do, sticks it on the machine and says "its good" "i cant give your money back" I thoroughly explained to him previously that it worked fine cold but not hot, and still that was the response I got.
Anyway, back to the wiring discussion. The wiring harness has nothing to do with the alternator failure, the exciter wire simply activates alternator, thats it. It either turns the alternator on, or it does not. If it does not then the alternator wont charge, but it does not make it fail.
I dont know if you work on your own car or not, if you don't ill help you out if you need it. I can get another one of these truck alternators and you can come up here and we'll put it on. I know its a about a 3 hour drive but if you need the help I dont mind.
Last edited by 00pooterSS; Jun 9, 2010 at 09:09 PM.
I do all the work on my car minus this warranty one 
. I got the car back today and checked out the wiring harness at the pcm. There was a little corrosion in the top left bank (when looking at the car) so I took it all apart, cleaned all the connections, dielectric, and started right back up with again no issues. None of the wires were frayed or burned out. Anyways, I got the truck alternator coming today from one of my salvage yards and see if it solves the problem.
Also, I did ask about the refund after they "fixed" the wiring harness and it was absolutely not, "this is just the next troubleshooting"
. I got the car back today and checked out the wiring harness at the pcm. There was a little corrosion in the top left bank (when looking at the car) so I took it all apart, cleaned all the connections, dielectric, and started right back up with again no issues. None of the wires were frayed or burned out. Anyways, I got the truck alternator coming today from one of my salvage yards and see if it solves the problem.Also, I did ask about the refund after they "fixed" the wiring harness and it was absolutely not, "this is just the next troubleshooting"
Teching In
Joined: Feb 2010
Posts: 24
Likes: 0
Can you do me a favor and look at my post and see if I am having the same problem ou were becuse if that is the case I will make the move to the bigger alternator here is my post https://ls1tech.com/forums/general-m...r-problem.html
I do all the work on my car minus this warranty one . I got the car back today and checked out the wiring harness at the pcm. There was a little corrosion in the top left bank (when looking at the car) so I took it all apart, cleaned all the connections, dielectric, and started right back up with again no issues. None of the wires were frayed or burned out. Anyways, I got the truck alternator coming today from one of my salvage yards and see if it solves the problem.
Also, I did ask about the refund after they "fixed" the wiring harness and it was absolutely not, "this is just the next troubleshooting"
. I got the car back today and checked out the wiring harness at the pcm. There was a little corrosion in the top left bank (when looking at the car) so I took it all apart, cleaned all the connections, dielectric, and started right back up with again no issues. None of the wires were frayed or burned out. Anyways, I got the truck alternator coming today from one of my salvage yards and see if it solves the problem.Also, I did ask about the refund after they "fixed" the wiring harness and it was absolutely not, "this is just the next troubleshooting"
Cool dude, just to make sure, did you get the 4 wire, 145 amp alternator from a 99-03? It has to be the 4 wire, I may have accidentally left that out earlier but I do not think the 99-03 had the 2 wire anyway so it may be a non issue.
Please let us know how this works out for you.
Last edited by 00pooterSS; Jun 12, 2010 at 01:33 PM.
Can you do me a favor and look at my post and see if I am having the same problem ou were becuse if that is the case I will make the move to the bigger alternator here is my post https://ls1tech.com/forums/general-m...r-problem.html
Finally fixed my multiple alternator failures. I used a 145amp alternator from a 2003 Tahoe, picked it up for $50. I also had to recharge my optima battery for 2 days to get it to full strength, cleaned every ground on the car, cleaned the pcm harness connections, cleaned the fuse box fuses and connections, replaced both belt tensioners and belts (which are alot tighter than the original ones), and replaced every fuse and relay inside the fuse box.
All the fuses in the fuse box under the hood had black hot spots on them but none were broken. I took the safe (expensive) out and just replaced everything in there. I don't know what would cause that?
All the fuses in the fuse box under the hood had black hot spots on them but none were broken. I took the safe (expensive) out and just replaced everything in there. I don't know what would cause that?