For my previous headunit I made a small electronic box that would control the accessory power input. It triggers by unlocking the doors, so while I was walking toward the car the headunit is already booting. This was helpful because the unit literally took over a minute before it was ready. Then I noticed on my father's car that when removing the ignition key, the radio on his bmw remains on and only when he locks the car, the volume would fade to zero. Pretty cool, I thought, so I bought the remote control for the clarion and sampled the IR commands for volume up/volume down. Then I installed an IR led and mimiced the volume up/down codes a few seconds after locking/unlocking the car. I really liked this functionality.
Unfortunately the same couldn't be said for the clarion headunit. After some months I threw it out and got a F60DAB instead. Massive improvement. But this one doesn't come with an IR remote, so the volume changing on locking/unlocking doesn't work anymore. I want to fix this of course, and it'd be a lot easier if I knew how to hack the steering wheel controls input for this purpose. Is there any information about this available?