Yamaha Digital Tach

The tachs I have only have 2 dip switches inside. My guess is that means only for 2 stroke, but need confirmation if possible. The model number on the box is 6Y5-8350T-81. Maybe it is not the right box. There are no buttons on the front of either tach.

[boats.net]

That would be an old gauge. It's only for 2 stroke engines with 3 wire trim sender(2000 and older), set both switches in up position for 6 pole alternator or first switch up and second down for 12 pole alternator.

Thanks for the quick response. The green card that came with indicated 3 switches,,,,funny. But you are correct in that switch one should be set to off if 3 wires to sensor and switch 2 to off if 12 pole, otherwise to on if 6 pole,,,,,question is an C85TLRP 12 pole?
Steve

Do you know if this will work with a 1999 250hp ox66

[boats.net]

The C85 is 12 pole alternator.
Yes that tach will work on the 99 250.