Loose wire identification on M817

Can anyone tell me what this wire goes to. It comes out of the same spot on the harness as the wire to starter solenoid.

What’s the tag number?

I did not know they were labeled. It was marked ground, so easy fix. Thank you

I'm pretty sure even though they're different trucks, the wiring is the same. Now that you know every wire has a number/letter/tag, should another electrical issue arise, it won't be an issue for long.