Electric Tach not working

[vigil]

So i have 2004 GS500 with an electric tachometer, bought it off a friend but the tachometer doesn't seem to work i asked him and he said its probably a wiring issue. Can someone please tell me how the tachometer works and what wire i should check?

[Armandorf]

Check the 3 wire connector and ground. Look for the wiring diagram. Maybe the wires are badly routed and are tense or stretching when turning the Handlebar and snapped.

[DarkCyDE]

Also the 3 screws on the back of the tach tend to get corroded