I may have an idea,,, and it may be a wrong cable problem..
3 pictures below, all go in the back of the pioneer D connector// notice the one for the old iPhone 4 has a audio cable going into the connector...the 3rd picture shows the audio being striped to a 3.5mm cable... Is that what we have? is that the problem?
picture 2 has the D connector but no striped out audio jack??