Not sure if this is the place to ask but I know you guys know these things.
This has been happening every since I've the boat (2 yrs) so not a new issue just one I've not addressed.
I notice that when I turn on the bow and stern lights (switch calls them nav and anchor)
The gauges read a little different. Especially the trim gauge.
This also happened even if I don't have the stern light plugged in. The trim gauge will read lower.
flip the switch off and all goes normal.
Amp draw issue maybe?