2000 Ezgo TXT pds wiring question

[ebro]

Hello, I am looking at the PDS wiring diagram from cartaholics and there is a wire shown that i do not have. It shows 4 wires coming from power harness going into the top of the controller..F1, F2, B-, and A1. The only wire I have on B- is the wire to the - terminal on the batteries which is shown separately so this cant be what they mean. What is the additional wire that goes to B-? could it be a ground wire? Help and thanks.