1993 Granada/Scorpio auto gearbox

My auto gearbox is acting the goat. After a short while the gearbox will not change up from 3rd to 4th. It's ok for a short time but when it gets warmed up the gearbox won't change up. Any help or suggestions - could it be the speed sensor ???

Brian.

:lol: :lol: :lol: :lol:
Fixed my gearbox problem - it was the Vehicle Speed Sensor at the back of the gearbox. £10 from the scrap yard.

Gear changes now OK as is the cruise control.

Thanks for the help given by fellow members.

Brian.