speedo help

[lisasuzanna]

my speedo doesnt work on my renault megane 1998 we had an ecu machine on it and that only picked up the sensor which i changed but still no luck my mechanic has said that it could be one of the three wires althou the two he checked had elec running through fine but cant get t the other one so he said it will mean having the dash board striped out to have a look which he recommended and auto electrician for. do you have any idea in how much this will cost me or any other causes for the speedo not working everything else works fine thanks lisa