The old (Japanese) screen unit in my JDM car was a Kenwood FGZ204F2 system with 4 ports/ harnesses into the back. As part of a plan to replace it with a home brew build, this post is just the outcome my working out what the various pins do.
Car interface and audio bus ports
Car Interface 16-pin Port (#1)
The interesting thing here is the CAN H and L pins. From what I gather this the same data that is going through the OBD2 port which also has these pins.
Hoped there would be a pin for the external ambient air temperature since that was displayed on the old screen. There is not, so it must come through CAN.
|3||ACC||Typically automotive accessory - the 'on switch' for the old unit?|
|5||CAN-H||CAN H & L are data protocol.|
|6||CAN-L||CAN H & L are also pins on the OBD2 port so guess data coming in here is the same|
|8||PARKING||Hand brake? Stationary. Neutral. Maybe nothing as my car is manual.|
|9||REVERSE||Think this goes poitive when car in reverse...for reversing cam|
|10||SPD||If this is speed, weird that its been given own pin, isolated the CAN data|
|11||ILL(PWM)||Illumination? PWM not sure|
|12||ILL(SMALL)||Ditto - something to do with backlight|
Audio Bus 20-pin Port (#2)
Camera and Navigation Unit
Navigation Unit 13-pin Circular Port (#3)
To do, maybe, probably will ignore this.
Rear Camera 4-pin Port (#4)
To do, maybe, probably will ignore this and replace with USB camera.