My speedo/tacho and rev counter have stopped working?

I have an iveco cargo 75e15 tipper. The speedo/tacho and rev counter dont seem to be working. the clock on the tacho isnt working so i assumed it wasnt getting power?. the fuses all seem to be fine. I did have a look at the gearbox sensor and came across 2 loose wires coming out of the gearbox with connectors on the ends of both, It looks as if their should be a wee sensor for them to both plug into externally. any help would be brilliant.