DIN8 Cd changer socket - factory radio

Hi

I have Chrysler Unit from 1998 and Ipod adapter and it works OK. My friend has similar unit made by chrysler with the same DIN8 socket and it is from 1999.

Sockets are the same, but the adapter does not work with his unit.

Do you know what difference is between those units.

I guess both use M-bus protocol to communicate. maybe there is just different pin-out.

Thanks for clue

http://wjjeeps.com/audiowire.htm
a quick search brought this up