Hi the dc-dc converter or dropper is behind the passenger dash
You gain access from the bonnet area on the right remove the black plastic cover 10mm bolts I think
I had this fail due to a poorly replaced windscreen leaking water into the converter killing it blowing fuse etc on dash left side I think..
I purchased an aftermarket one and that's what mine runs on now
Hope this helps. Craig...
craig
January 2013