The system has 3 selectable heights and a 4th system selectable height.
Access - the lowest - is user selectable
Standard - the normal driving height - is user selectable
Extended - the highest - is user selectable
Motorway - around an inch lower than standard - is selected by the system once you are going over 60 for longer than 30secs.
You will get a bong and a message about speed when in extended height.
If there is a fault in the system it won't moan about speed it will just say AIR SUSP. INACTIVE and you'll either get the hold light in centre of the selector switch (soft fault which be automatically reset once the fault goes) or no lights at all (hard fault which will need diagnostics to reset).
The switch has 5 lights, one at the top, two in the middle, one at the bottom and a fifth in the centre of the height selector switch.
Obviously these lamps indicate the ride height selections and the one in the centre of the switch is the ride height hold button.
If the light is lit that indicates the current ride height, if it is flashing that indicates the destination ride height i.e. bottom light solid you turn switch upwards, the middle light will now flash to indicate the destination height, once the height change is completed the bottom light will go out and the middle light will now be solid.
Lets say you want to stay at the middle height and not allow the system to automatically drop to motorway height press the middle of the selector to activate the height hold light, this will freeze the system in the selected ride height.
If you in access height and pull away the system will automatically rise to standard, if you press the hold switch while in access you are now in crawl mode which allows you to drive the car in access mode where there is limited head room, but it will cancel the hold command if you exceed 20mph(?).
If in extended height and you exceed 30mph the system will lower itself to standard.
If the system is in motorway, you can press the hold switch to lock it in motorway height so it won't rise when you slow down below 30mph for longer than 30secs.
If your getting a speed message more than likely your in standard and selecting extended.