I have an 05 LTD with JBL/Nav and had the Pioneer AVH-2550 NEX "professionally" installed. I use quotes because they did a crap job, can't even watch videos with parking brake on. Another issue is that the subwoofer isn't really working. It's working, as in it makes noise but I can only hear it if I'm standing right next to it. It's not loud and punchy like it was before installing the aftermarket unit. They used PAC RP4.2TY11 harness which is supposed to maintain factory amp. Fade and balance work. I'm about to tear it apart to fix the parking brake issue (going to bypass it altogether). Does anyone have any suggestions as to what I should do to troubleshoot the subwoofer issue?