Tach inop

[Kaykatz]

I just bought a boat with a C60LTRX motor, with a 703 remote. The Tach has 4 wires, black, purple, blue and grey. The purple wire has battery voltage..... 14.9v when the motor is running. The grey wire has 5.9v. The purple wire has 0.01v and I'm guessing that the black one is ground. What do I need to check in order to get the tach working?
I'll post a picture as soon as I can.

 

[Kaykatz]

No Title

 

[NYBo]

Purple: + from ignition switch
Blue: + for the internal light
Gray: signal from motor
Black: - "ground"

If you have 12 volts (or more with motor running) between the black and purple, the problem is the tach itself, the rectifier on the motor, or the gray wire.

 

[Kaykatz]

Thanks so much for the info NYBo, looks like l have a bit of digging to do. What should the Voltage be between the black and purple wire be.

 

[Barnacle_Bill]

Purple wire should have battery voltage on it with the key on.