Are there alternator settings for '07-'10 e38's with Bosch 125a for engine swaps?

Have a 2007 6.0/6l80 with a 2010 GMC e38 computer, swapped into a 1971 Chevy K10. It has the Bosch 125a alternator. In the process of tuning, and having issues with the truck not charging. It slowly head dead as I drive it.
Had the alternator checked and they said it charges at 12.8 volts. The guy who checked it(local Napa was the only place with a testing machine) looked at me with the "deer in the headlight" look when I asked him if a varied input changes the output.. Inconclusive on that one..
There isn't a voltage control unit fitted since its a swap, but I'm not sure what to change the alternator settings to? I've tried two alternators and the main power wiring for the alternator is 6 gauge going to a junction block on the firewall feed from the starter terminal. Everything is soldered and shrink wrapped, so I know there's no lose connections. Commanding the L term in the scanner will cause the volt gauge (Dakota Digital VHX) to slowly rise, but not very much at all. Do I need to wire it to keyed power with a resistor life I've done with others in the past, or hopefully just adjust the calibrations?
I'm sorry but I'm at a different shop with no Wi-Fi right now, so I can't attach a log or file. I've got a file in my most recent thread from a few days ago. Need help to figure this out while the truck charges tonight!

Please help!

Is there a battery sensing wire off the alternator that go's directly to the battery.

There's just the main charging (heavy gauge) wire to the battery, then the two pin plug with pin pin #61, circuit 23 ( .05 brn)- charge indicator signal
Pin #32, circuit #25 (.05 gry) - generator field duty cycle signal
The descriptions are cut short on the Editor, and I cant read the full information, and there's nothing in the help section under "System" for the alternator, which where the settings are in the Editor.
We recently swapped an '04 LS2, and had to put keyed voltage with a resistor in the line in order for it to work properly, but that had a Holley ecu. I can't find anything anywhere on the alternator settings or specifics for this one.

Are any of the alternator terminals labelled F or L? Do you have a picture or model of the alternator? The E38 does a great job running an alternator when it's setup for it...but depending on what you have and need, it may be possible and simpler to wire the alternator like an older car.

You can't make those alternators work like the older ones. They use a PWM (pulses) to command a Duty % for the regulator. There is no way to emulate those pulses without the BCM or the GBCM. For Gen4 stuff you need the BCM and the battery current sensor (the module with the ring on the negative wire). Without them the ECM won't send a signal to the regulator and it will go to default mode, 13.8V always (regardless of consumption)
You have 2 options:
1- Install the BCM and charging sensor, wire them and get charge control (I have done it and it's a PITA).
2- Install an older alternator and set it for single-wire charging (much much easier)

There is nothing you can change in the tune to make it charge without adding those modules.

FWIW, I have done several swaps on older cars with this alternator and no BCM, not a single issue yet. 2 of them have like 6 years as a daily drivers and not a problem with battery charge. Those cars don't have heavy sound equipment, just the normal stereo and lights

I know of another shop near me that is installing a '13 6.0/6L80 combo in a .70 Olds Cutlas, without a body control module, and without the voltage sensor, and he said they're not having any low charging voltage issues. He couldn't say what is different as they had an outside source modify the harness and flash the ecm, but only that theirs is charging just fine. For this project there's no way I'm going to mess with the BCM, and I'm not sure what you're referring to when you reference a "GBCM"?
I've thought about dealing to an aftermarket one wire alternator, but would that mean just eliminating the L and F terminal wiring, and disabling the DTC's, or is there an earlier LS alternator that I can use.
It's disappointing to think there's no way to make this work after all the other hurdles we've been through making everything else in this combo work...

The GBCM is the "Generator Battery Control Module"

They are not having low voltage issues because it works fine. As I said, it charges to 13.8V without any input from the ECM, all the cars and trucks I have installed this alternator to work fine.

If yours charges less than 13.8V then it's bad or you have another issue.

I know he said he does have the meter or clamp around the battery cable, but I haven't personally looked at it yet to tell.
I ended up taking a spare attempt to a local generator shop and having it converted to the earlier Delco style regulator for about $90, which is better than mid $200's for an earlier alternator that's only 105 amp. Wish there was a way to make it work as is, but until somebody makes a module for swap applications..

During our LS engine swaps on Jeeps I have figured out how to control the alternator without a BCM. We have a canbus module that will send the proper signal to the PCM. The PCM will then command the voltage output.

I have been on the fence about releasing a module for general LS swaps. Its a very basic setup and could even be made to just plug into a OBD2 port.
Give me some feedback if you think this is something that would be needed.

We ended up just taking the alternator to a local generator shop and having an older style regulator put in it. Added the 370 ohm resistor in the keyed power wire and it worked perfectly. Cost was right about $80 and included bearings and whatever else they do when they rebuild one.