2001 ford superduty diesel wiring diagram

 I am trying to install a sony amp to my existing factory radio in my truck. It is a combo am/fm/cd/cassette.  I have purchased the line converters and both a new harness and reverse harness so I will not have to cut wires. My problem is that when I look at the original harness that plugs into the radio it has an extra wire going into it.  It is located in pin position 11 according to the replacement plug diagram..The wire is red with a blk stripe... and the replacement plug diagram states its one of 2 open slots...can anyone tell me what that wire is and, if I need to, how to connect to it......  thanks....Larry

Im sorry I looked at the pin location wron I believe it is pin or slot 14