1999 S150 Tach Gauge

[ken52]

I have two fused lines under the helm that connects to the tach. They both have a 10A fuse. One is yellow and one is red. Anyone know what they are from?

[99yam40]

here is a quote from a thread just below your when I looked just now.
Maybe it will help

http://www.yamahaoutboardparts.com/f...am-th2841.html

Grey = Overheat Sensors from the motor
White/Blue Striped = Fueltank Quantity Sender
Black = Ground
Yellow = 12v w/Ignition ON
Blue = Nav Lights+
Red = 12v Continuous (Fused under cowling)
Green = No Charge from Engine - Warning Light

[ken52]

Thanks, I did see that thread but he has a speedo and mine is just a tach, also my understanding is that my green is a tach signal and the other thread has green as a no charge from engine warning light. So that's why the post.

[99yam40]

I would think that the red and yellow are the same as theirs.
12v + and 12v+ key on. Easy to check with a meter.