Pioneer DEH-P7000BT

I have a Pioneer DEH-P7000BT. I can connect my iPhone 5 just fine. I can play music on BT Audio just fine, I can recieve calls, works perfect. When I turn my truck off then back on, I can still recieve calls through it perfectly. However, when I turn my truck off/on, The iPhone won't auto connect to the BT AUDIO. It just says no connection. I have to manually reconnect everytime, I turn my truck off. It is driving me insane. Other peoples phones auto connect perfectly. The problem is the iPhone 5. Any soloutions? I just don't understand, how it can not be connected but I still recieve calls through the head unit no problem. Help, please.