Yamaha 50 HP Outboard motor with unconnected cable. What is it for?

[phabej]

I bought a polar kraft boat with a Yamaha 50 HP two months ago and being first time boat owner I failed check the speedometer before purchasing the boat. I got the boat home and realized that the speedometer is not working. Any idea what could be wrong? Is it something that can easily be fixed? I also noticed that there is a wire hanging loose in the motor that was not connected to anything. See attached picture of the cable. Should the cable be connected to anything? Could this be the cause of the speedometer not working?

 

[Silvertip]

That cable has nothing to do with the speedometer since it is not electronic (except for the internal light. That cable is likely for an accessory item that this motor doesn't have/need. Speedometers are pitot driven meaning there is either a separate pitot (generally a white or black plastic) device mounted on the stern of the boat. That pitot has a small hole facing forward into which the water pressure pressurizes air in a small plastic tube going to the speedometer head. So the tube is either pinched, split open or the pitot is plugged (most likely). Some engines have a pitot built into the lower unit to which that tube is connected. Same principle and same issue -- plugged pitot.