(Incomplete...I'll add more later).
DIY: Play external video source through the rear view camera input (Aka...torque app on the brz headunit)
Thanks to foobar and others on this thread for helping:
http://www.ft86club.com/forums/showthread.php?t=46379
Why I did this:
-I don't want to spend money on a new headunit and I don't want to spend money on gauges yet.
-I wanted to be able to see what was going on with regards to oil temps and coolant temp (in descrete units).
Why you don't want to do this (some of which might not apply to you):
-The resolution is crap. You will be down-converting HDMI to composite and it may not look pretty.
-The rear camera input has a caution warning and guidance markers that overlay on the video and you cannot (at this time) get rid of them.
-The head unit will not always switch into reverse mode on demand. Sometimes it will fail and you will have to restart the head unit by entering the diag menu. However, one you enter the diag menu it seems to switch back and forward between reverse and normal just fine.
-Your phone won't ring because it will have all of its audio pushed through the hdmi connection. This is ok if your phone pairs with the bluetooth of the stereo, but not if it disconnects every 5 minutes (like mine currently does)
What will I need to do this (complete parts I used to get stuff from phone to head unit):
-An android phone – I have an Atrix HD which has a dedicated micro hdmi connection.
-A bluetooth OBD II connector ($cheap on ebay)
-Torque Pro or Torque lite
-A cable that lets you output video from your phone – will be different for different phones ($5)
-An HDMI to composite video converter ($30 on ebay or amazon)
-Spare wire
-butt connectors, vamp clips, and or heat shrink tubing
-A crimper, wire stripper, a soldiering iron, etc.
-An old RCA (composite) cable ($0)
-Spare female pins from a pc fan or new ones from mouser/digikey/etc.
-An SPST switch
Some of the stuff you will need:
Steps:
-Create the RCA cable – take your old cable, strip it and attach the sheathing to your ground connection and the center will be your signal. I opted to use new female molex (ish) pins I had laying around for easy of use.
Stripped RCA cable looks like this:
The stuff around the outside is called the shielding and goes to ground
you can usually find the female pins you will need in old fan connectors
Soldering will give you a more reliable connection
-Put two long wires on your SPST switch.
-Take your head unit out of the car (see the other DIY's here:
http://www.ft86club.com/forums/showthread.php?t=8585 and here:
http://www.ft86club.com/forums/showthread.php?t=49631 )
-This is how you use the fancy molex connectors on the back of the headunit:
http://ae64.com/Pin_insertion_extraction.htm I used a bent up pointy piece of metal.
-This is a diagram of what you will want to wire up:

-Put the ground pin of your RCA cable in pin 16 of the 16 pin connector
-Put the signal pin of your RCA cable in pin 8 of the 16 pin connector
-Wire your spst switch from pin 2 of the 28 pin connector to pin 7 of the 16 pin connector (Camera 6V output...meant originally as the power supply for a backup camera). This will allow you to fool the system into going into reverse mode at will (sort of).
-While you are in there you might want to (if you have an older firmware version) do the unlock trick that lets you view movies, use all menu items, etc. while driving). It is here:
http://www.ft86club.com/forums/showthread.php?t=15239
-Plug your HDMI to RCA converter into a power source (you may want to wire it to 12 volt outlet and hide it under the center console. There is plenty of room there. I would test it out first though.)
-Plug the RCA cable into the converter and the HDMI cable into your phone.
-Plug in your headunit and test it out before buttoning everything up.
Video:
[ame="http://www.youtube.com/watch?v=owsrApBPuQM"]brz with OBD II data on stock headunit (using torque, hdmi to rca converter, etc.) - YouTube[/ame]
will do better video later