I recently got an appradio3 and had a 5 pin automotive relay kicking around. I was able to use the relay as the bypass without any additional components such as the TR7; this is done by utilizing the 5th pin(pin 87a) wired to the car's parking brake switch.
In the past, you can wire 4 pins (30,87,86,85) on a relay 5pin relay or a 4pin N.O. (Normally Open) relay to simulate the parking brake being engaged. This no longer works with newer firmware as it requires the parking brake to be engaged, released and engaged again; hence the need for the 2 pulse bypass.
30 to the deck's parking brake detection wire (light green)
87 to ground
86 to ground
85 to power antenna/power amp (Blue/White)
87a goes to the car's parkingbrake switch.
The workflow to get it to work is as follows:
1) Before starting the car, ensure the parking brake is engaged (typically done when you park).
2) Start the car, push OK on the deck and once the screen loads you release the parking brake; this will simulate the first two required steps, grounding and release.
3) Plug in the MHL (I have a samsung s3) usb into the phone and click Apps; at this point, the power antenna wire (blue/white wire) will turn on and engage the relay, simulating the final step.
4) choose to ignore the connection loading screen or you can wait; either way you will get to the screen to click OK.
If you fail to have the parking brake engaged prior to starting the car, don't worry you can still activate it. Start by unplugging the adapter from the phone and plugging it back in.
When you do this, it will kick you back to the main screen and the power antenna wire will stop powering the relay; this will simulate the first two steps, grounding and release. Plugging it back in and clicking apps will engage the relay, simulating the final step.