Bad pcm or software bug? Control module voltage issue

[2000_SS]

I have a ls swap project with a P59 from a suburban with a 2 bar OS in it.

Logging control module voltage (sae) showed 8.4 - 10v at idle and picked up to only about 11v with rpm. Alternator and battery test good.

I have 14.2v virtually everywhere i check under the hood (some places have 13.4v) and at the obd2 port, only the vcm scanner shows low voltage.

I swapped to a spare PCM i had laying around and now control module voltage showed 0.0v while the truck is running.

If i remove control module voltage (sae) in the vcm scanner and replace it with the generic control module voltage pid, it now shows 13.7 - 13.9v.

I now noticed equivalence ratio commanded (sae) shoes 0.02lambda. i add the generic equivalence ratio pid and it reads 0.93 lambda as it should (engine not warmed up).

Is this a bug in the software or do i not understand SAE vs generic pids? I'm extremely nervous about proceeding with tuning because i had a junk aftermarket engine harness roast one bank of pistons on a turbo car while the other bank looked overly rich. I fixed the harness after finding the pathetic wiring job and we went from a 350hp 5.7 to a 535hp 5.3, changing only to a smaller displacement short block and harness rework. The owner didn't pay me for the job and i just let it go, but don't want that to happen again....

[2000_SS]

I went ahead and removed the SAE pids and continued tuning, cautiously. The truck made 477/470 on my MD500 on 11psi and 12* on 91 octane, SBE 5.3 with a small cam. Control module voltage and lambda generic pids were reading what i would expect/hope and nothing blew up, so i'm guessing there's something i'm not aware of happening here regarding generic/SAE channels.