OK so following the logic about what each pin is from jcdillin at brewtroller and the info from the board pinout in the installation manual
I get this.
From pinout on installation manual
HLT - MLT - KET Switch Headers (JP1,2,3)
I assume this is the same for JP1-JP16 on the relay board
1-2 = Auto
2-3 = Manual(ON)
0-0 = Off
Pin 1 = BrewTroller
Pin 2 = Relay
Pin 3 = Ground
On a switch when pin 1 and 2 are closed BrewTroller is in control (auto)
when pin 2 and 3 are closed you have manual control (on).
Then my drawing should look like this, the left side represents 2 NO contacts on the back of a 3 position selector switch, the right is the schematic from a 3 pin header