Locomotives on DCC layouts require a decoder to be fitted to control the motor direction and speed. Additional functions are available on most decoders, usually function 0 being used for directional lighting. DCC Ready locomotives are fitted with a plug-in socket for a decoder, check which type is needed for your locomotive, usually this is shown on the end of the box and operators leaflet. Locomotives without a socket can be fitted with decoders by direct wiring or by fitting a socket on a harness. Reference to Peco decoder installation Shows You How 20 booklet is recommended for guidance.