Land Rover Repair: Disco 3 Suspension, proper test, rocker switch

Question
Good day John,
I trust you are well.
My 2008 disco 3 v8 HSE does not lower when the rocker switch is operated.
It does go up when the swich is activated to lift the vehicle.
Once at the high suspension setting it only lowers when the speed goes up - it gives the message that it will lower if speed is not decreased. It shows no fault messages.
The symbols by the rocker switch does not light up when the lowering function is selected but does light up when the vehicle is raised.
Regards,

Answer
The problem in this case may be as simple as a faulty switch but you cannot do any meaningful tests without one of the Land Rover diagnostic systems.  Generic scan tools won't talk to the air suspension.   If you are far from a shop with proper test gear I'd suggest swapping the switch.  Beyond that I suggest you wait to get proper test access.

If you travel into remove areas you might think about converting the truck to coil springs so you are not at risk for air suspension failure far from home