I upgraded the stock radio in my 1999 ML 430 to a 2003 MCS I purchased from eBay. I was happily surprised to find the wire harness plugs to be the same. The radio and cassette player work fine, but the CD Changer is not detected and has no power to eject the magazine. I suspect the wiring is different. What can I do get the CD Changer operating again?

 

The 99 cd changer was probably not using the same type of wiring as the new command module. The new command module reportedly only supports newer accessories such as the changer and sat radio which are set up to use fiber optic cabling rather than the conventional wiring that most autos used for the last several decades.