the light on your VDO will stay "ON"....
on the e7,e8 n e9 there is no indication provided for the ayc.only the acd will have a fault indication n that is if all the acd mode light lite up.for the ayc,u can check physically n the symptoms are difficulty to start or accelerate on slippery surfaces.but a sure way to chk the ayc is by diagnostic device MUT-II.u can even do the AYC and the ACD ops test with this device.
usually its the acd pump or the 4wd ecu.seldom the light assembly.try hooking up the MUT-II tool lah.it will give out the fault code n u will know which component is defective.