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I've read all threads regarding doing the upgrade and how to do it thats not a problem.
My problem is i just want to confirm if this is the correct alternator it came off a 2004 express 2500 as per threads get a "2003-2004 truck alternator"
Its 4pin 145amp i just dont see where the battery wire plugs into? Am i missing something here lol.
Should I return it and get something else before even taking out my old one and realizing it doesn't work.
That post with the nut threaded on in the upper left of the picture is where the power wire from the battery goes.
Whats up SS thanks for the reply.
so what you're saying this will work? because i thought there was a battery plug that actually plugs into the back of the alternator and then a ground wire. Do both go there on that post?
Battery wire only. Wouldn't make much sense to hook a battery wire and a ground wire together, now would it? unless of course you were deliberately trying to start a fire?
The case is usually grounded by being bolted to the motor. There's hardly ever a separate ground wire.
Not sure about that other plug though... that usually connects to the car somehow. A "truck" alternator, such as my 04 Avalanche, doesn't have wiring and a plug like your photo. I'd take it back and get one that looks about the same but with no plug plugged into that spot.
Don't be surprised if your vehicle throws a DTC P1638 code for Terminal F if you get this slightly wrong. Just kill off that code in your tune and understand that you might be giving up PCM control of your alternator output. No big deal - just check your alternator output with a multimeter. The internal alternator voltage regulator will still function.
I got everything in went smooth everything
buttoned up
but now the Guage is right down. here are the readings with a multimeter DCV @ 20.
105amp alternator 12.55 with car off
14.44 with car on
14.2 with lights radio fan on
145amp alternator 11.92 with car off
11.83 with car on
11.44 with lights radio fan on
With the old alternator the car would struggle/grind to start with the new one it starts up right away all day long back to back with no struggle or grinding,
that being said maybe i ruined the battery? Relying on the battery to start the car with the old alternator? Note i got this battery last year
But what doesnt make sense is that the numbers with the old alternator are in perfect range. Now with the new one they are way off.
Any insight will help kind of buzzkilled was excited for this mod. I hope its as simple as changing the battery.
P.S when i say "new alternator" i mean a 2004 alternator out of a salvaged truck. Technically not new lol.
When car is just on, fan light stero off Car on with lights stero and fan on
Your "new" alt is not working. If it was, the voltage would be higher with the car running and the alt charging the batt, than the batt voltage by itself. It won't be starting AT ALL for very long, struggle or no.
Not sure what you mean by "received without the plug". That kinda looks like it's part of the alt, internally.
Still looks like the thing to do is return it and get one that didn't start out life with that. Have them look for a truck in the 04 - 06 range with RPO code KG3.
Or, just go to yer local CT or whatever you have available, and ask for the alt for such a truck. They're not much $$$; not much sense in dinking around with a junk one, really.
The plug thats in the picture of the alternator is the same alternator wire from my car that plugs into it 4pin wire.
This came from lkq which deal with salvages cars they must of cut it off the truck when they removed it therefore thats why it was still plugged in. But when i received it in my possession that plug was no longer plugged in
06-26-2020, 12:48 PM
Ls1 truck alternator, did i get the right 1? 
