Tachometer does not work

[gaslighter01]

I just installed multifunction tach on my 2004 f115. All the dipswitches are set correctly which is up down up. trim and tilt work, oil works, the tach only works when i am trimming the motor. As soon as i let off the switch the tach zeros. Checked all the wiring checked the trim and tilt relay. everything looks ok. checked the control box for shorted wires with no luck. Also note that the rpms work when i trim from the switch at the motor. Anyone have any ideas?????