I am must be stupid, tach wiring twins ?

[Holy Smoke]

My tach's where faded and I decided to replace them, so I replaced both tachs, removed one, plugged it in to the harness, and did the same
with the other.

Now my starboard tach reads correct and my port tach reads the starboard motors rpms.

If I turn on both key switches start the port motor rpms show the same on both tachs WITHOUT THE starboard motor even running.

How is this possible,? not sure how I could have screwed this up.

I am going to pull the tach wiring apart tonight apart tonight to see what is going on but its plug and play so I am not what I could have screwed up

[99yam40]

If these are smart meters you will need to program / set them up

[Holy Smoke]

If these are smart meters you will need to program / set them up

I wish, no these are the plain tachs for a 2004 150 hpdi