R_O_M
Guest
Check the ground speed impulse reader and the disc which is mounted on the end of gearbox shaft. you may have too much clearance there to pick up the impulses that are generated as the holes in the disc pass the reader. If the disc is bent or warped, only one side may be reading. We changed our MPH readout to kilometres per hour on our R62 by making a new disc with 13 holes drilled into it rather than the original eight holes. Took a couple of hours to convert. Rolf got into the adjustments on the side of the steering console and using a GPS, adjusted to a very accurate ground speed readout. Time moves on and we now use a cheap bog standard GPS unit for ground speed readout.