The VR1.5 plugs into the auxiliary connector of TCS T series decoder.
Where wiring is necessary the blue and black/white striped wires are the power supply lines. The blue wire connects to the +12v decoder function output, the black/white striped wire connects to the function negative, common or ground.
The tan coloured wire is the +1.5 volt output for the lighting circuit. The other side of the lighting circuit is connect to the normal decoder function negative.