[migrator]

Does the head unit retain any pre-set stations after being switched off? If it does not then it is likely that the two power supplies have been swapped. The 'constant' supply is to let it retain the pre-set and CD position info. The switched supply is to make it run. If the switched supply is connected to the memory circuit any installed CD will always start from the beginning and you will need to manually tune the stations. (This is how the Volvo units that I use are working - I have assumed that other manufacturers will have the same sort of basic set-up.)