UK Car Repair: omega speedometer, electronic speedo, electronic vehicles

Question
hi my omega 1997 2.5i 16v the speedo clock when you drive off just goes round to 110+ mph and when you stop it returned to zero can you tell me what causes this please and the remedy if possible thanks

Answer
It is an electronic speedo and the problem is most likely in the dash unit.  There is a signal generator on the transmission which sends the feed but it would not appear to be that. You have to take it to someone who can test the system. ps; it is worth checking all of the fuses as odd things can happen in "electronic" vehicles.