Speedo sensor on a Renault Clio 1.2 16v 2001 model? ?

Where is the speedo sensor on a Renault Clio 1.2 16v 2001 model? Gearbox or ABS sensor? Speedo is reading very high - 45mph at 30mph and ABS light comes on when braking ordinarily. Turn off the iginition and light goes out until you brake again. Are the two problems connected? All help gratefully appreciated.