The incident involves a 2018 toyota highlander v6 awd that was purchased new on june 1, 2018. as my 12 year old son was buckling himself into the 2nd row driver-side seat today, the seat belt ripped apart in his hands. the sudden-motion locking mechanism never engaged, and no undue force (except for what one would expect from a normal 12 year old) was applied when pulling the seatbelt from its stowed position. when i personally inspected the remaining seven (7) seatbelts, both the 3rd row driver-side and passenger-side seatbelts failed under minimal stress (far less than my full body weight or strength).