wiring oil warning lights

[ruffinit]

I have a Yamaha analog tach with the three oil warning lights. I am trying to determine where four leads from these lights go. I assume black goes to ground, then there is a green and a green w/red stripe that match up with the wiring harness from the motor. That leaves a yellow lead....... does this go to yellow (switched +12v?).
I can't figure out what's really going here, and I would appreciate any help. I'm ready to give it up and take it to the dealer.......................