Help to interface a digital motorcycle tach

Discussion in 'The Projects Forum' started by Jack_K, Aug 18, 2009.

  1. Jack_K

    Thread Starter Senior Member

    May 13, 2009
    I want to add a tachometer to my motorcycle. I have a tach from a 2003 Harley Davidson Ultra Classic motorcycle. According to the HD service manual, the tach gets its input from the bike's ECU (computer). I've been told that the signal is a 500 usec pulse from the ECU. I can't verify that since I don't own a Harley.

    I think, if I connect it to a coil on my bike, it may destroy the tach. So I need a way to change the coil pulses to clean 12 volt pulses that are 500 usec wide.

    Any ideas?