[ybmug2]

I have a 1992 Yamaha 175 HP with the multifunction tach and speedo. The tach works fine, but the speedo stopped working. The backlight comes on, but there is no display for the speed or the bars on the side for the fuel. The backlight on the guage works, but there seems to be no other power to the guage. I checked fuses and breakers. There is a white wire that is not connected under the dash. Can someone tell me what that wire is for and if there is an internal fuse in the guage?

Thanks

[jl_photo]

what kind of speed sensor do you have?

are you sure it is working?

[ybmug2]

The sensor is built in to the lower unit and I believe it uses water pressure to show the speed. The gauge used to work, but does not seem to have any power to it. I am not too concerned with the speed as much as the fuel level which is also on the gauge. I am looking for a wiring diagram because some wires are not connected.

[Yamajoe]

The white wire from engine to the remote control box main switch off and for engine stop switch.

[rodbolt]

never saw a combo speed tach, on the speedo you will have a white and a white with a blue stripe, they are for fuel sender input.
one is for the US sender the other for yamaha senders.
so one wont be connected.