2005 focus door wires

Hey All, was working on a 2005 Ford Focus, and the info I have was to locate the wires for door trigger above the passenger kick, and use all four wires with diode isolation. I had no problem locating the wires ( exactly where my info said ), but I found that all four wires had a negative on them even when the doors were closed. I measured with a dmm and I also let the interior light time out just to make sure. Just out of curiousity I did hook up one of the wires to the door trigger input of the r/s,and sure enough it set the alarm of right away, even with the door in the closed position. Any ideas on this or other thoughts. Any help would be appreciated. 

                             Thank-you in advance