The last thing that needs to be dealt with as far as wiring goes is the function/set up button. One end will be hooked to a ground and the other end to the brown wire of the speed/tach harness. The button needs to be installed in an easily accessible location. We drilled a small hole under the dash to the right of the steering column and put the button there. We could still reach it while driving but it's out of plain view. This button will be used to put the gauge cluster into set up mode to calibrate the tach and the speedo, but more on this in a second.