How to detect and rectify an air leak on an AS Tronic Shift Actuator

This blog post has been created to show you  how to diagnose an air leak on an AS Tronic Shift Actuator, how to remove the faulty part and what to do about a replacement.

This information is also available as a video here.


Feed air into the system. This can be done either from the vehicle’s pneumatic air feed (if the unit is still connected to the vehicle) or using an adaptor attached to a pneumatic air feed (if the Shift Actuator is outside the vehicle).

Once an air feed has been established, watch the four holes to one side of the gear box (indicated by fluorescent strips on the image below).

shift actuator fault test
If air is blowing right through the system, air will come out of these holes. This indicates that the bottom half of the Shift Actuator is faulty.

air blowing through actuator system

Removing the Shift actuator

Now you have identified the bottom half of the Shift Actuator as the cause of the problem, it needs to be removed and replaced.

If the unit is still in the vehicle, first make sure you remove the electrical connections from the clutch actuator and the vehicle itself.

Remove the 15 headed 13mm bolts from around the outside of the housing. It does not matter which order you undo these in.

unbolting the shift actuator housing

The bolts come in two different lengths. Shorter ones can be found at the back end of the shift actuator.

  • Once removed, put the bolts to one side for easier fitment later.
  • When you are undoing these bolts, you will notice is that the front end is spring loaded, so the housing will lift a little (the longer bolts are found at this end).
  • The complete actuator has now been released.
  • Because we are only changing the bottom half, first we need to remove the lid (the actual brain of the ECU) from the faulty bottom half.
  • Remove the two T30 Torx screws from the unit.

removing actuator lid

 T30 Torx screws

There are slots on the side of the unit. Carefully tilt the upper half towards you and place it in these slots.

AS Tronic actuator dismantling instructions

This reveals two ribbon connections. Care needs to be taken with these as they are fragile.

actuator ribbon connections

Gently rock these ribbons back and forth until they come lose from their ports.

loosening the actuator ribbon connectors

There should now be nothing connecting the top and bottom halves of the unit. Place the top half to one side until it is time to refit it.

When these units fail, the central piston is normally in the neutral position so just check this as it will be important for when you re-fit it.

checking piston is in neutral position

Lift the complete bottom half away, being careful of your gaskets.

removing bottom half of actuator


You can order a service exchange bottom half from Ecodrive Transmissions by calling our team on 01204 701812. The bottom half can be fitted straight back onto the unit without any programming issues for the AS Tronic lid.