Im trying to install a shift light that runs off the tach. I need to find the wire that feeds the signal to the tach does anyone know which one it is or a better one to use?
just test each wire lead of the harness. know your shift point on your tach and rev it once you get a voltage reading at the shift point you know what one to splice. our mazdas though are not dedicated voltage traps though they kinda are wierd if you use a shift light. like pulse flashing and what not. good luck.
