Gen2 To Gen1 position

[ChrisG]

So I have determined that the gen 1 alt is actually the gen 2 alt that previous owner must have put there assuming they were the same. I really dont want to buy another alt so whats it take to make the gen 2 alt work properly in gen 1 position.
Is it just removing the insulators in side the alt and hooking block ground to bolt on back of alt? Its at the alternator rebiuld guy right now and he seemed to know what to do just want some other input.

 

[Evil Dr. Porkchop]

The two alternators should be the same (both setup for isolated ground). The gen 1 alternator should have a wire connecting the ground post to ground on the truck, thus making it operate as if it was a "normal" alternator.

 

[Warthog]

From the factory GM installed the same alternator on both sides of the truck. That way the military only had to stock one type of alternator.

To make the isolated ground unit work on the drivers side(GEN1) they added a ground wire from the ground stud to the engine block.

 

[ChrisG]

Okay. Now that makes sense. So I just ran down and grabbed the alt before he made any modifications to it,it is currently set up to work in the isolated ground config like it should be. The above picture is exactly how the rebuild man said to hook it up yesterday afternoon.
However it had the ground strap going to a bolt in the back of the case like a traditionally grounded alt which is wrong im gathering, the ground wire has to be the threaded stud like in pic.

 

[Warthog]

As you have discovered running the wire from the block to the alternator case is the incorrect way of hooking up an isolated ground unit.

The whole idea of "isolated ground" is to separate the internal components from the case.

 

[ChrisG]

Yes im getting it slowly...thank you again for your assistance Warthog. Mostly just correcting what was wrong from previous owner...no wonder he was sick of it and sold it. Its all there though just got to keep troubleshooting and get things the way they should be.
Sooo do you think that this is why the gen1 light is not coming on ie. incorrectly grounded or not at all as the case may be? I will be throwing it on at lunch and will report back.

 

[phil2968]

Chris, make sure the ground wire to the coolant crossover stud is tight on the stud. It has to have washers to tighten down on the terminal. The nut will bottom out on the threads and appear tight but the wire will still be loose without the washers. Ask me how I know! Chased that voltage problem for a couple of weeks before I discovered what I had done.

 

[Warthog]

If the GEN1 alternator had the fiber washers installed inside the case and did not have the ground wire on the ground post, it would never work correctly.

You would be amazed at the number of people with new trucks that contact me to help them "fix" the creative wiring that the previous owners did. Trucks that came from fire departments are the worst.

With a stock system many of us can help diagnose just about any electrical issue via pictures and troubleshooting. Deviate from the stock wiring and it is all a guessing game.

The stock system works (of course there is room for improvement). Some of the creative wiring makes my head spin.

 

[ChrisG]

Yes the alt had the washers in place I was right there when the rebuild man pulled it apart, the ground wire to engine was just in the wrong spot. I think the previous owner didnt realize it was a isolated ground alt and just hooked it up like a regular vehicle would be.
Iam going to have new battery cables made because the ones on it are trashed what size cable should I have them made up in?

 

[Warthog]

The stock cables are 2 gauge. Some member have used even bigger.

 

[cpf240]

Thought I'd read this somewhere before...
http://www.steelsoldiers.com/showth...REAR-battery&p=1683628&viewfull=1#post1683628

 

[Warthog]

I was referring to ChrisG needing to start his own thread with all his truck issues.

You have been around long enough to be a BIG help to the members. Thanks for helping out.

 

[cpf240]

I was referring to ChrisG needing to start his own thread with all his truck issues.

You have been around long enough to be a BIG help to the members. Thanks for helping out.

No worries Warthog, I saw your suggestion that he create his own thread, and completely agree. I just thought it was funny / ironic that I had just mentioned the issue of the GEN 1 ground cable being connected properly.

In the end, what really matters is that the problem gets fixed.

 

[ChrisG]

First off thanks for your help as well cpf240 it is very much appreciated that you take time out to answer and comment on my somewhat repetitive line of question and answer dealing with this issue ...now that the formalities are out of the way.
Went home got gen1 hooked up as it should be connected batteries no big sparks,that seemed like a step in the right direction. Got in turned key on both gen lights come on start truck volt gauge shows needle in middle and steadily climbed into green.
Put multimeter across both batts and got 28ish volts and each batt showed 14.3. with truck running and had same at back of alts.
I'm thinking that this issue is resolved and in hindsight all i really needed to do was put the ground in the right spot on gen1.
Thanks again for the troubleshooting help...

 

[Warthog]

14.3V at each battery is a good sign. It does sound like the ground wire was the issue all along.

Good job.