Trying to go NMEA2000 on my XS. Currently have a Smartcraft Tach. The rear has only 8 pins. Connector to gauge has female with 10 openings but only 9 wires. There is a black and yellow that is not connected but appears on n wire harness. Thing is a mess. My question is. I am hooking up the existing Smartcraft female to a Smartcraft 4 position hub. My plan is to then either feed my Smartcraft tach or a Vessel View 502. Is there power going FROM THE Smartcraft fitting through the 4 port junction box or do I still need to provide power to the NMEA2000 network. I am afraid to provide power twice.

I was going to power the network and hook the connector to both the back of my Garmin 943xsv and then run from junction box to either the tach or the 502.

Thanks in advance
Tom