CD Player Connection - how does it know there is a CD player and how can I trick it

[d215yq]

Hi, have an old Sony radio with CD control cable that goes to the boot (picture of cable). Long ago I unplugged the audio leads from the CD changer, rerouted them to passenger compartment and fitted a 3.5mm jack so connects to phone for audio.

So if i want to listen to music on my phone I put the radio to CD player and it plays the CDs in the changer merrily on repeat while gettign the audio straight from my phone and playing that out the speakers. All good but 1) sometimes the CDs give error so it beeps every now and then and 2) needs the CD player connected so a waste of space in the boot (radio knows there is no CD player when not connected so wont play any music).

So, is there anythign I can do to that cable to mimic the CD player (e.g. put a resistor between two pins or short circuit two pins?)

 

[LostKiwi]

There's s digital serial communication takes place down that link. It can be mimiced (there are usb music players that do just this). Nothing so simple as a resistor though.

 

[d215yq]

Thanks, I'll put that into the too difficult box for now...if I'm going to buy something I'll probably just get a head unit with aux for 50 quid. The sound quality is generally poor but I am assuming that is the original speakers (particularly front ones) than head unit..