Thanks kindly for all your replies.
Mine does not have a mechanical speedo, it is electrical and yes I am referring to the gerabox speed transducer .
I have checked the TPS on my multimeter and it appears to be fine, however your tip is good and i'll try it.
I have also checked the water temperature and fuel temp sensors and all appear to be good.
Ill get the car up on axle stands and check the transducer as soon as I get a chance.
Ill report back with the findings as I get them.
Many thanks to all, great forum chaps.
