I. Planning

1. Introduction

Hi folks! It's my first post here. After seeing the audio display connector pinout from the service manual, I believe it's possible to add a composite video input for screen mirroring easily to the display using the wiring for the back up camera. the display for the base model doesn't appear to have any other video inputs except for the back up camera since it directly communicates to the radio; however the dual screen models (possibly also 13-15 models?) has a dedicated video input connector that might be able to be used for aux video (I can't test it since I have the base model.)




Disclaimer: This project is very experimental. This post is only used to document my own progress on the project and is not intended to be a guide. Please make sure you are able to solve any potential issues that may arise. I'm not responsible for any damage done to your vehicle or any injuries.

2. The connector(s)

For the base model with the single screen, the upper display has three connectors, only the big 32 pin connector is used for the video input.


I used pin A14, A16, A18, A19. The basic idea is to short A14 to A16 to trick the display to show the video input from A19, which can then be connected to either the backup camera or the aux input.

For cars with dual screen, there is a dedicated video connector, I'm not sure if it's for the backup camera only but I attached the PDF for the connector pinout.

3. Wiring:

This is how I wired the video input to the display. S1 switches between the actual reverse signal and a constant 12V source and feeds either into A14 on the display connector to enable the video when ever the S1 is at the 12V position. S2 switches between the video signal of the aux input and the backup camera and feeds the signal into A19 on the display connector. Both video signals share the same ground and are both connected to A18 on the display connector.




It should also be possible to use the reverse signal to switch between the two video signals by replacing S2 with a relay. something similar to this...


The actual processes will be followed below...

 

4. Taking the radio apart.

I followed the service manual pages that's attached to the post for the disassembly. I took some photos but not for the connectors because of the tight space, but it’s basically just splicing the wires and adding switches following the wiring diagram above.

Photos for the process:

The display after the visor is removed.



32 pin connector




Verifying the voltages for the video signal.

5. Connecting everything


Soldering the switches


After connecting the switches I was able to turn on the backup camera even not in reverse.


The RCA jack I used


6. Testing

After I finished the wiring, I connected my VCR to test the video input.



7. Buttoning everything up




I added two holes on the display visor for the switches.




Finished!



8. Conclusion

Now I can watch my favorite VHS tapes or play the NES in my Acura RDX! All jokes aside, I will receive a HDMI to RCA adapter on Monday and I will add android auto using an old phone next week.




It would be nice if the lines for the backup camera can be removed.


Where I got the idea from:

https://www.instructables.com/Car-Re...-as-Aux-Input/

 

nice work ! to remove the lines for the backup camera, you can go to dianostics mode\camera menu.

 

Be interested in the Android auto....if you get it working.

 

I tried to use an old phone to run the headunit reloaded app and mirroring the screen through an HDMI to RCA converter but it's not a very stable just because of the number of software involved, so I ended up just mirroring my phone that's running the stock AA app and control the phone with a trackpad. If you're phone is rooted you could probably have a script that turns off the phone screen and connect to the car's Bluetooth when you start screen mirroring.

 

There's a lot that isn't evident in the factory documentation, regarding what's really going on at either end of these connections that you're interrupting.
For example, no guarantee that the signal that indicates "in reverse" can actually source enough current to drive a relay. Also, that there isn't something else that is infered by the presence of the "in reverse" signal (beyond selecting the backup camera feed).
You should also determine if the switch (or relay) you are using is make-before-break or break-before-make as it can have consequences for the devices to which it connects.
And, ideally, use a mercury wetted device to ensure the switch doesn't bounce (again, because you don't know how the devices will react to seeing "in reverse; no, not in reverse; yes, in reverse; no, not in reverse" several times in the fraction of a second that it takes for the switch to change state.
Without more detail of the internals of the devices on each end, it's hard to know what's safe; the better approach is to build an electronic "veneer" over all this stuff so the veneer can operate independent of what the car designers wanted (i.e., interpose between the car's electronics and the display so you can take complete control of the display, without the car ever knowing what you are doing!)