Yamaha 6y5 Tach gauge 'was' working fine

[SaltyKayak]

I have a 2003 F115 4-stroke all with the original Yamaha gauges. Up until 2 weeks ago it was working great showing the hour meter, temp sensor and oil sensor and of course RPM's. Then for about a week, the tach began displaying sometimes and cutting off while cruising only to come back on when at idle or after sitting for a time. Then, this week.. no hour meter reading or tach reading. Yes there is power when I turn the key on and all the indicators on the gauge come on but tach stays at 0 when engine is on.
Where do I start to narrow down the problem and fix the tach?

[NeverSea]

Now I have the same problem as you.
I just bought a secondhand boat

[Mozella15]

A completely dead tach could be caused by many things. But yours is intermittent and that means there is a high probability that you have a wiring problem. It could be something else of course, including the tach, but I would check the wiring, including the connections, first. Begin by looking at the connectors. If one is loose, it could very well cause your problem especially since the tach dies or comes alive when conditions change. If the connections are good, you might have a wire chafe problem or a wire corrosion problem, neither of which are uncommon on boats.
The good news is that fixing bad wiring might be inexpensive, even free. And it might be easy too.
The Bad news is that finding an intermittent connection can drive you mad and it could turn out to be very time consuming. And, it's important to remember it could very well be another problem such as an internal connection inside the tach.
Good luck.

[NeverSea]

A completely dead tach could be caused by many things. But yours is intermittent and that means there is a high probability that you have a wiring problem. It could be something else of course, including the tach, but I would check the wiring, including the connections, first. Begin by looking at the connectors. If one is loose, it could very well cause your problem especially since the tach dies or comes alive when conditions change. If the connections are good, you might have a wire chafe problem or a wire corrosion problem, neither of which are uncommon on boats.
The good news is that fixing bad wiring might be inexpensive, even free. And it might be easy too.
The Bad news is that finding an intermittent connection can drive you mad and it could turn out to be very time consuming. And, it's important to remember it could very well be another problem such as an internal connection inside the tach.
Good luck.

It's about up to an error. 28 Shift position switch i checked with YDS
That puts the RPM on tach I'm dead

[99yam40]

It's about up to an error. 28 Shift position switch i checked with YDS
That puts the RPM on tach I'm dead

I am not sure what this is suppose to mean