U have to sync ur phone with iTunes & add some music b4 App Mode works!
Hey Dairian22, thanks for that little tidbit of information, that's the KEY piece of information i've been racking my head over for the past few days (read below for long winded story if interested, im sure you will all get a good laugh, I did after the fact!) I don't recall reading that ANYWHERE in the Pioneer's owners manual for the AVH-P4300DVD!
I've had my Pioneer since March 2011 and was using it with my iPhone 4 16GB iOS 4.1 JB'ed (which only had one mp3 on it that I had put to test the deck feature out of curiousity since I used the SD slot for my MP3's and the iPhone ONLY for App Mode since I have too many games that I only have 1GB left for music
)....then in January I wipe my phone and put iOS 5.0.1 and JB it again, App Mode kept working fine even without any music on the phone. Now comes two weeks ago, I wired up my leather heated seats that I swapped in my car so I had to disconnect the battery since I was disconnecting the passenger airbag sensor module in the seat. After the work is done, I configure my Pioneer again and attempt to use my iPhone in App Mode a few days later, it no longer wants to go into App Mode! I start reading online and see countless of posts of people reporting that after iOS 5, their App Mode no longer functionned and they had to take an old iPod/iPhone with iOS 4 to "kick start" the App Mode feature and then the iOS 5 device could be used (but this had to be done everytime the key was turned off). I asked my brother to borrow his old iPod 2G JB'ed (which had music on it) to test the theory and concluded that I was screwed and needed to buy myself a iOS 4 device since I didn't want to downgrade my iPhone back to iOS 4 (I didn't know still it was the music which was the key factor here). Then I noticed that as long as you left the receiver in App Mode, even after the key was turned off, you could return to App Mode with a device on iOS 5 (well actually a device with no music on it). At that point I was convinced that what I read was correct so I start looking for an iPod 2G device. In the meantime I took my daughter's iPod iOS 5 JB'ed and downgraded it back to iOS 4 and was ready to buy a new one for my daughter when I test it out only to find out that even downgraded to iOS 4, it did not work!! (still no music on it as it was a fresh restore) Then I find a 2G 32GB, buy it only to find out it also did not work (no music on it). I figured maybe it needed to be JB'ed as well in order to work, I do as such and still no go. At this point I was out of ideas and couldn't figure out why my brothers iPod 2G worked and not my 2G 32GB. I was about to send an email to Pioneer when I found this message board and decided to sign up to post this experience to see if anyone had solutions. But like anyone should do before posting a question, I decided to use the forum search feature first and found this post. Right away I put an MP3 on my 2G 32G device and to my amazement, it was now launching App Mode!!
With that said, I felt I should come on here and thank you along with sharing my story to hopefully help the countless of other's who obviously don't know this as I've seen by reading on different forums!! Thanks again!