I wouldn't start this without the wiring diagram, table of standard colours (which might not match yours) and a multimeter. I'm not really sure how to interpret the diagram! Where have you got stuck? Is it with the colours, the numbered ways in a schematic or something else? Switch one way gives water temp, in middle nothing, other way reads oil. is that better than a two position switch? Wasn't there a discussion about whether to use one that sits in either position or one that is sprung to water but can be manually held over for oil? ... Black/ Green is conventionally "Relay to radiator fan motor" but again might not be in your car. I'd test that directly. Jonathan