The Japanese model differs in some connectors from the European model.
Connector 5 is a rear view camera in the Japanese model.
24-pin connector is responsible for the handfree system and aux connector.
The 20-pin connector can be easily converted into a 24-pin connector by purchasing the connector and soldering to the connector wires 20-pin according to the wiring diagram.
Try using the service manual and wiring diagrams: https://www.insightcentral.net/forum...nuals-pdf.html