Pretty simple really, the wire that normally goes from the ignition switch to starter solenoid goes to the neutral safety switch first then to the starter solenoid. Makes a connection only in park and neutral, open circuit in any other position. The switch on the floor (and column actually) can be moved a bit to adjust where your floor shifter is in neutral and park. Best best is to set the trans in neutral and check for continuity, then in park. I use the continuity feature of my cheap multimeter for this. Adjust the position of the switch as needed to get continuity only in park and neutral.About to install a NOS Safety Neutral Switch, Floor mount today. I was told this is the reason why my backup lights don't work? Any tips or advice??!