Non-working tach and hour meter

On my new 1995 Sport Nautique (pro Boss GT-40) the Tach and hour meter are not working.

I'd like to attempt to figure out the issue myself but really don't know where to start. I was hoping to get a few pointers here. I have a voltmeter and I'm willing to learn how to use it. Note: The depth gauge also doesn't work but I am not too concerned by this. The other Gauges appear to work fine.

Also the Tach is stuck at about 600RPM and tapping the screen didn't do anything.

As a side note I plan to replace the Tach with a PP Stargazer but need to determine if the issue is with the Tach or the wiring before I attempt this.

So where do I start with this. How do I determine if the gauge is reviving a good signal of if the problem is from something else. If it is something else what is this likely to be?

Finally one quick question: I want to replace the Tach with PP Stargazer, partly because I think the Tach is broken and the speedo's work find but also because I prefer the look of two speedo's. Any reason why most people appear to replace a speedo, rather than a Tach?

Here is a pic of the dash, because I know you like pictures.

Not having a wiring diagram makes it hard for someone who does not have much electrical experence. But I'd start at the hour meter because if I remember correctly it only has 2 wires,a power and ground. With the key on see if you have power to that gauge. If not I would guess you might not at the tach and the depth finder either. From there you would just have to start tracing the wiring and seeing what is going on.On mine all gauges come on with the ignition breaker,the depth finder is on a seperate breaker. I don't know if all boats wire the depth finder the same since I think they originally came with a clock and maybe the dealer installed the depth finders? The tach also has a switch on the back which also seems to affect the working of it,if you get inconsistant readings ie jumping or too low or high a reading you can move that switch back and forth several times and returning it to it's original position it will cure that trouble. As to where to install thats up to you but I would replace a speedo before the tach but I have seen it done your way before.

Move the 4,6,8 switch on the back of the display a few times and put it back where it is. You'll be all good then.

MartyMabe wrote: Paul, You need a PEF Plaque for that blank space on your dash pod

yes I do. I have these on my to buy list but I first need to get the boat down from Canandaigua.and then I am going to clear/restore what I can.