I've got a japanese nav unit and display on my bench that's currently hooked up to a logic analyzer. All signals from the nav unit seem to output correctly and I can see the display is active, all pixels are on and displaying black but the backlight is not lit.
I'm wondering if the display is waiting for a "wake-up" command because the nav unit thinks the dash cover is closed. For a 2005 system the "Power Cluster Lid Amp" sends this control signal to the nav unit which in turn activates the screen maybe... Problem is I dont have that part so don't know what type or signal or waveform is required. The manual doesn't list a any reference values for it either.
I actually own a 2006 UK car with nav that doesn't depend on this, but I'm just experimenting right now to see how much can be reverse engineered... Eventually I may just gut the spare nav unit and pack a Pico ITX computer with slot loading DVD drive into its shell, mount this to the passenger side rear deck and integrate this to the OEM screen, nav controls and sound system.
Anyway, I'm just getting started so not much yet but here's some things of interest:
- The display unit seems to have multiple signal input configurations. On its PCB, there are markings for RGB, RGB sync, horizontal sync and vertical sync, TV and DVD input lines. Some of these output pins are unused and not documented in the service manual.
- The RGB sync rate is somewhere between 14.5khz - 15.5khz which suggests a CGA display so quality may not be the best.
- The "RGB Area signal" as written in the manual could be video luminance signal because its marked as "Y" on the PCB