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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)
Pin | Function | Notes |
|---|---|---|
| 1 | +B | Always on 12V |
| 2 | GND | |
| 3 | ACC | Typically Automotive (ACC)essory, the second stop on ignition key. Sends power to the old unit. |
| 4 | GND | |
| 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 |
| 7 | IGN | Ignition. Maybe another stop on ignition key? |
| 8 | PARKING | Goes position when handbrake on. Typically pulled to GND |
| 9 | REVERSE | 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/light? PWM is normally 'pulse width modulation'. Not sure |
| 12 | ILL(SMALL) | Goes positive when head lights are on (for back lighting of unit) |
| 13 | NC | Not used |
| 14 | NC | Not used |
| 15 | PTT | No idea |
| 16 | GND |
The interesting here is the CAN H and L pins. Must be the same data that is going through the OBD2 port, and how the old unit got speed, trip data etc.
I 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.
Audio Bus 20-pin Port (#2)
Pin | Function | Notes |
|---|---|---|
| 1 | ||
| 2 | ||
| 3 | ||
| 4 | ||
| 5 | ||
| 6 | ||
| 7 | ||
| 8 | ||
| 9 | ||
| 10 | ||
| 11 | ||
| 12 | ||
| 13 | ||
| 14 | ||
| 15 | ||
| 16 | ||
| 17 | ||
| 18 | ||
| 19 | ||
| 20 |
Camera and Navigation Unit
Navigation Unit 13-pin Circular Port (#3)
Going to delete this – think it fed to GPS and some Japanese centric traffic stuff.
Rear Camera 4-pin Port (#4)
An analog video signal. Going to delete this and replace with USB video