In December, NHTSA updated FMVSS 208, Occupant Protection Systems, to require a seat belt use warning system for rear seats. The agency also updated the existing requirements for the driver’s belt warning by extending the duration of the audio and video warnings, and it applied the driver-seat requirements to the front passenger seat.
The front seat requirements will go into effect for vehicles made September 1, 2026, and after. One year later, vehicles will need to meet requirements for rear seats as well.
NHTSA determined that a regulation was needed because warning systems have been shown to save lives, yet many vehicles lack them. While manufacturers voluntarily equip nearly all new vehicles with front passenger seat warning systems, only 47% of MY 2022 vehicles have a warning system for rear seats, where seat belt use rates are lowest.
Therefore, the new rule will require a visual warning on vehicle start-up to inform the driver of the status of the rear seat belts and an audiovisual change-of-status warning to provide an alert if a belt is unbuckled while the vehicle is in motion. Click here or enter Docket No. NHTSA-2024-0071 into a web browser or at www.regulations.gov to read the details.
Will the rule benefit child passengers?
NHTSA’s intention when writing the rule for the rear seat system was to ensure it benefits children, aiming to better protect both booster and nonbooster users (including those who have transitioned to a seat belt prematurely). The agency estimates that the addition of rear seat belt warnings will save the lives of over two dozen children under age 11 per year, as well as many older children.
To ensure that children benefit, NHTSA’s compliance testing will require a system to provide warnings about belt use by an average 6-year-old. Manufacturers may use the 6-year-old crash test dummy to ensure they meet this requirement or, if they prefer, a person who weighs 46 pounds and is 45 inches tall.
While some vehicles already have rear seat belt warnings, the final rule suggests that some of the existing systems will need to be upgraded. Many current systems have targeted detection of at least a 5th-percentile female, following existing European criteria. However, NHTSA notes that using the 5th-percentile female as a threshold excludes most children ages 6 to 14 and some children ages 15 to 18.
Will the systems affect CR installation?
Although the benefits for older kids are certainly worthwhile, CPSTs should note the potential for false alarms when CRs are installed using the LA attachment. These “nuisance alarms,” which are already an emerging issue, are likely to increase as rear seat belt warning systems are added to vehicles or made more sensitive. In the final rule, NHTSA declined to require that systems be able to distinguish a child in a CR installed using LATCH from another passenger.
Instead, NHTSA states in the final rule that the easiest and most effective solution to avoid false warnings for LATCH-installed CRs is to fasten the position’s seat belt behind the CR. NHTSA notes that it already encourages this practice at www.NHTSA.gov, and some vehicle manuals provide consumers with this guidance.
However, the final rule does not require vehicle manufacturers to provide this guidance in owner’s manuals. CPSTs looking for written guidance can refer to the LATCH Manual. At the beginning of each vehicle manufacturer’s entry in Appendix B, a bullet in the bullets section describes the manufacturer’s current rear seat belt warning features, along with any manufacturer advice for how to make these systems coexist with LATCH-installed CRs.
Therefore, learning how to secure an unused seat belt when a CR is installed using LATCH will likely become increasingly important for families and CPSTs. Buckling the belt behind a CR is the most common guidance, but some manufacturers say running the belt through the CR’s belt path is allowed. Whatever solution is used must not interfere with proper CR installation, and currently unforeseen issues could come to light.
The standardization of this vehicle technology is another reason to encourage caregivers to keep items like groceries, diaper bags, and other cargo on the floor, in the trunk, or secured using a seat belt. Fortunately, this practice aligns with established best practice for preventing projectiles.