A vehicle trailer backup assist system and method includes a hitch angle detection apparatus and a target monitor controller. The target monitor controller processes images acquired of the trailer towed by a towing vehicle to assist with placement of a target on the trailer. The target monitor controller also monitors the target and provides feedback to the user as to proper positioning of the target on the trailer. A target move detection routine detects movement of a target by processing the pixels of the image to determine if a new trailer has been connected. Further, a trailer connection monitoring routine monitors for a changed trailer based on loss of the hitch angle or target for a predetermined time period.