2000 Yam 150 OX66 VST power

[jb123]

a friends 0x66s vst is having intermittent power issues going to vst pump. where does this 12v come from, comp or keyswitch ? are there any connections inbetween ? e checked 10 pin main and was ok.
now that i rethink the issue he needs to check grounds also.

[boats.net]

JB
The power comes from the main relay when key is on but the ground comes from ECU, bad grounds is the most common problem with electrical issues.