Sorry I’ve not explained it very well
The head unit is the same the only change is the Bluetooth harness that connects to the back of the head unit was not there before and since it’s been fitted the screen displays the word “disabled”
I can't remember but when i brought my intravee (plug in the trunk) I had to unplug my Factory iPod device (plug behind the head unit)
It seems that all device that you plug emulate a cd changer, so you can't have both