Tachometer trouble

[BassnG3]

My tach for my 1999 150 VMax doesn't register at all. My voltage readings are as follows: grey wire-5.8volts and purple reads 14.8volts. Not sure what the readings should be and I am trying to figure out if it is my tach or not. Any help would be appreciated.

Scott

[boats.net]

Yes the voltage looks good