Question:
Can gearchanges be controlled by the gear position sensor only attached to their gearbox?

Answer:
The 9A range of ECUs have a wide range of powershift options that can be configured from a Single Cut to a Full Closed Loop Control set up and in the most advanced options can rev match.

The problem with trying to do a gearchange with a gear position sensor only is that the threshold required to trigger a gearshift is very small and any noise that manages to enter into the signal either from an external device such as a coil or alternator or even slack in the transmission can make the ECU believe that a gearshift is being requested and because this is its only means of input, it has to believe it. Therefore the problem is that the ECU has to cut engine power even if the driver is not touching the gearstick or paddles, and the driver then thinks they have misfire. So we do not use or recommend this strategy.

We recommend the following; use either a switch in the Gear knob or in the gearbox or a strain gauge, then when the switch sends a ground signal to the ECU Powershift pin (stain gauge changes voltage), the ECU knows it is ready to do a gearchange. If it is a Single Cut only, this is sufficient. On more advanced set ups such as Fully Closed Loop, the gear position sensor then gives information to the ECU as to how far the gear drum has moved and it can make decisions based on this information. For more advance options such as Closed Loop, we suggest that you contact one of our agents who can either set it up for you or provide remote technical support to set it up on your car. We can carry out this kind of work for you, but you would need to have had your car wired first.