Wire in trans tunnel
 

What is the wire that is hanging in my transmission tunnel to the old trans. What does it control? I know stupid question please bear with me. thanks for your help. Oh 1988 t2

reverse sensor + another sensor for the transmission.

2 wires run to the neutral switch (side of trans). Usually blue.

4 wires run to the 5th gear/ reverse switch (back of trans). Usually red & green.

Or, if it is a J-spec trans, there is no 5th gear switch, so there will just be 2 wires running to the reverse switch.