Need help identifying pcb wire terminations

So I am switching out custom motor controllers for an ebike. But need help identifying the purpose of the wires indicated on the pcb.

In the pics I have highlighted the appropriate acronyms with its wire color. As you can see right off the bat I have one problem. One controller has 6 wires for throttle and the other has 5. Identifying what the heck these acronyms stand for, is my first problem. I'm sure more to follow lol.

So I know Rx is receive, tx is transmit, n is neutral, gnd is ground, P is for power, etc.

But what is SK on the one pic? And what is SD and VCC on the other pic?

Btw they are amazon purchased, Chinese manufacture, so no wiring diagrams or schematics available.

VCC is voltage in or positive(usually red wire) as I normally say. GND is GND/negative(black wire usually)

Do you know which wire is going to what, that could help some.

Unfortunately I am not certain but, on the 6 wire board, it definitely went to a throttle with hall sensor and kill switch. The 5 wire, I think is supposed to be used with an LCD. I'm thinking there is no making these compatible

Also the colors of the wire is next to each termination. On the pics you can see the abbreviations like tx, rx, FCC, etc. But cant provide more info than that