Anyone know what this sensor is?

[Jason 56]

I have a 2016 L83 8L90. I’m reworking my own harness. The sensor ( picture #1) has a loop that wraps around the negative battery cable. I assume it’s a amperage meter of some sort. I looks like the loop on a alternator load tester. It doesn’t run into the ECM, just to the BCM. That being said... I’m guessing that it doesn’t need to be part of the stand alone harness. Also was wondering if pin 48(blue connector) is the proper brake signal I’m going to need? Any help would be appreciated! I threw in the other 2 pictures so you can see what I’m working on.