" Wayne..... Normally there is
" Wayne..... Normally there is no relationship between the tilt/trim setup and the tachometer, and even if there was, I would think that any conflict that might exist would be constant rather than exist only at a certain rpm.
There may be other ways that a trim unit could conflict with the tach, but the only one that I can think of at the moment is if the power supply to one or the other was improper.
This could be a case of having 12 volts being supplied to the tachometer purple wire (normal), then as the voltage passed through the tachometer and exited via the black ground wire.... instead of having that black (ground) wire connected to ground, it was used as a 12 volt source leading to the tilt/trim unit. This would have the PTT unit being the sole ground source, and when the PTT switch is engaged, obviously that would have an effect on the tachometer.
In your case, if the 12 volts power supply is proper leading to both units (Tach & PTT), I would suggest that you check and clean all related connections (such as if you were just now installing that component) in order to eliminate any possible weird voltage backfeed problems.
Joe (30+ Years With OMC) "
