Where should I connect the separate single black wire (marked with "S") so that the display knows if the Turbo SW is pressed (i.e. it changes between high and low values)? Initially I thought this comes from either of the Turbo LED jumpers on the mainboard, but I tried and it didn't work.

What I have done so far:
- Powered up display using the regular 5V connector
- Set the display to show the correct value (at least one of the values)
- Turbo LED is powered directly via the yellow/white wires (not sure about the H/P/L pins though)