Eprom

Does anyone know which sensor in the gearbox is used for speedo pickup, when you view the car from the front, there is a sensor on the right hand side of the box large plug on it. There is also a sensor on the left hand side of the box which goes to two plugs.
Car is a MY99 UK Checked all the plugs and interconnections but speedo and mileage does not work, it’s just had the clutch changed, but works intermittently.
However car flashes up engine light then.
Also posted in technical.