M923A2 Alternator wire help

[Plugugly]

Hello, new member and new M923A2 owner here, looking for a little specific help on my truck. I have a wire that is cut and zip tied to the heater hose by my alternator. The label on the wire shows 568, which I found the info on that by searching here, and reading the TM's. It should be the field excitation wire, but my alternator is working fine per the gauge and meters. What I think happened is I have 566 and 568 switched somewhere, so the ignition switch is exciting my field but I don't have overcrank protection, which is what 566 is for. I'm thinking this is working because both wires just want to see voltage, and both of these should be interchangeable in that regard. This is just my theory, I hope someone can tell me if that's true, too. The starter will over run, but my alternator is making voltage. To me that means that the alternator side of 568 is seeing voltage, 566 is not.

The problem I'm looking for help with is identifying where the non-alternator end of 568 is on the actual truck. I've seen it referred to as going to the "brain box" on the drivers side of the firewall, but if someone could direct me to the exact terminal or show me where both are supposed to be routed, maybe I can find the real 568 and 566 and get them sorted. I couldn't find the wiring diagram for 568, but I saw the one for 566 and a generic schematic won't help me as much as someone that knows right where the wires should be so I can focus my search.

Other than that, thanks in advance for the help, I'm loving the truck so far.

 

[doghead]

Schematics are typically in the TM that ends it 20/24 and 30/34.

 

[juanprado]

566 does not do anything. It goes to the "F" terminal of the pcb (protective control box) but according to the p2p -is not used at all.

See the diagram for 568

 

[Plugugly]

Well, first post and first mistake all in one day. I went back to verify my wires and look for the routing, and found that 568 is indeed connected to 568. The wire that has no end and is zip tied is also coming from the harness, not the alternator. It is 566, so it's not connected to the alternator. This was all in loops behing the alternator, so I didn't see what I thought I saw until I straightened it all out with better lighting.

Doghead, thanks for suggesting the TM numbers, what I wanted was not a schematic but a picture or explanation. You can see from the great schematic that juanprado shared that it doesn't really show where the wires are going in the real-world truck.

Juanpprado, thanks for the schematic, that is different than the one I saw out of the TM, where 566 went to the back of the ignition switch. I guess going by that its not necessary to connect 566 at the alternator at all, which is probably why it's zip tied there and taped.

Cheers, and thanks again. I guess my truck doesn't have a mystery wire issue after all, it's like an appendix.

 

[bogshotrods]

OK guys, I had to send my alternatror back for warranty and didn't take a pic of the wires under the little cover that the weather tight pig tail comes out of. There are to other posts that are under that cover 1 is a 1/4X 20 and the other is a 10X24 and there is a wire that comes up by the starter that goes to 1 of those posts but I'm not sure whether it's the 1/4 X20 or the 10x24. Not sure how to post a pic here to show what I mean so excuse the confusion.I think the wire in question is the POS wire

Thanks in advance for any info as the TM is rather hard to see where that wire goes

 

[dawico]

OK guys, I had to send my alternatror back for warranty and didn't take a pic of the wires under the little cover that the weather tight pig tail comes out of. There are to other posts that are under that cover 1 is a 1/4X 20 and the other is a 10X24 and there is a wire that comes up by the starter that goes to 1 of those posts but I'm not sure whether it's the 1/4 X20 or the 10x24. Not sure how to post a pic here to show what I mean so excuse the confusion.I think the wire in question is the POS wire

Thanks in advance for any info as the TM is rather hard to see where that wire goes

Is this what you need?



Hopefully this helps. Let me know if you need to see anything else.

 

[bogshotrods]

Well that's what my burnt up 1 looked like, then I got a rebuilt and it burnt the stator after a year and I sent it back to Florida for warranty with the a wire hooked to what I think was the 1/4x20 post to the left next to the pig tail wire in your pic but it didn't come back with that wire hooked up just the weather tight pig tail is there, but I don't want to take a chance on hooking what I think is the POS( positive) wire to the wrong post and do more damage as they did the warranty for free and it would be another $275.00 + shipping if I hook up the wrong wire to the wrong pole.

Thanks again for the help

 

[Retiredwarhorses]

The ring connectors correspond to the size of the terminal...one is ground, one is pos, and one is super small, then there is a female rubber connector that goes to male on the wiring harness.
assuming this is a 60amp alternator.
i just replace the 60amp gens, the cost to refurb is the same or more then Picking up an NOS or take out unit....
there is a lot of rebuild kits for the 60amp for sale...so if,your handy, that's one way to go.

 

[bogshotrods]

OK you pretty much confirmed what I was thinking that it's the POS wire terminal, the other really small wire is for A/C from what I saw on a TM the alternator company sent me,

Thanks so much or all of the reply's time to get it back on the road before diesel goes up any more here in CA