Wife's car, 2011 4.6 bought new and now has 127K and still running fine. Had the alternator replaced a month ago. Yesterday car behind bumped the rear and the headrests deployed. Although I prefer to let the dealer fix the headrests and other slight damages, I couldn't let her drive around with the headrests like that in the mean time. So I searched this forum and found the reset procedure to fix the driver side's one only. Didn't want to reset both as there were some broken plastic bits.