Smiths tacho not working - The 'E' Type Forum Mar 31, 2016After looking into my wiring diagram I belive I have a current sensing RVI tach. The white wire is a feed from a fuse into a loop inside the tacho, it then goes directly to the + side of the coil. After searching the internet I have not seen any other smiths tacho wired this way. Smiths Instruments Classic Car Gauges SMITHS Classic 140mph Digital Speedo. Smiths Classic digital 100mm (4in) or 80mm dashboard fit 130mph speedo, odo or trip readout, on board "drive-to-set" programming, full range of matching dashboard instruments to return any classic or kit-car dashboard to pristine condition. Rev Counter Wiring!? - Problems, Questions and Technical Dec 15, 2008I have a period Smiths 'Pod' type rev counter from the 1970's that I eventually want to fit to my car - my Mini already has an aftermarket tacho fitted, and it has ONE wire going to the coil. My period Smiths tacho has TWO white wires, just like the diagram that was kindly attached to this thread.