NEMA 2000 SMIS Gurages Quit Working

[shallowaterhunter]

I have a 2007 DF140 and have two SMIS guages. Two trips ago one of the guages (#1) quit working but the other one (#2) worked. This weekend both worked for a few minutes, then the (#1) guage went off after a few minutes then the #2 guage went out. Neither one of them are working now. Any ideas what could be causing this?

[Moonlighter]

Can you be more specific - are the SMIS displays totally blank, with no backlight?

Or?? Turning on, but only has dashes instead of data?? Or something else?

[shallowaterhunter]

They are totally blank. They lit up on Friday, one was bright the other was kind of dim and then they went totally blank. They don’t flash at all when starting up. I don’t think it’s the gauges, that would be too coincidental that they both go out at the same time. I checked the connections and connectors at the engine and all appeared to be in order.

[Moonlighter]

The gauges are powered by their connection to the NMEA2000 network.

If the network loses power, the gauges will not operate at all - as you have described. This could be your problem.

I suggest you get behind the dash, find the cluster of T pieces that make up the network, and find the T piece that is connected to power. 2 wires: pos and neg (typically red and black) will be connected to that T.

Usually they tap into a spare connector in the engine harness for the pos wire so that the network is powered on and off by the key. The neg wire could go to a negative busbar. You need to find where the pos and neg wires are connected, undo the connections, clean them, and then test with a multimeter or test light that the wires are getting power and making good connections when the key is turned on. A test light should show a good strong light. Any dim light indicates poor power and a possible wiring issue in the boat eg corrosion inside a wire somewhere, even a bad battery or corrosion on the battery terminal.

See how you go with that and report back.

[shallowaterhunter]

Is that power connection usually done at the engine or under the console? Just trying to figure out where to start looking.

[Moonlighter]

As I said, it is behind the dash (console), where you will find the cluster of network T pieces.

If you look at the back of the SMIS gauges, there is one thick cable running to each gauge. Follow them, they will lead you to the T pieces within a couple of feet.

[shallowaterhunter]

I understand that and know where they are, i was asking if you thought the power connection (black and red wires) were connected to power behind the console, where all of the power connections are, or at the engine where the NEMA cables terminate.

[shallowaterhunter]

Thanks for your help..

[Moonlighter]

Behind the console.