I'm installing an AVHP4200 in a chrysler 300....the installation went well except the unit will not turn on with only the 12V constant power "yellow wire" is hooked up....it only turns on when the ignition 12v wire "red wire" is also connected to the yellow wire....so all in all four wires are interconnected just for the unit to turn on......the problem with that is the unit will not turn off when the ignition is turned off........I'm I doing something wrong with the connection or is it the harness???????