In most cars, the seatbelt warning light will flash or emit a chiming sound when you or another passenger does not have their seat belt fastened. The seatbelt warning light may also come on if the seat has too much weight.
NHTSA seeks comment on the effectiveness and consumer acceptance of enhanced seat belt warning systems, including whether they require occupant detection and where the visual warning should be located.
It Detects Unfastened Seat Belts
Seat belt warning systems use sensors to detect the presence of a passenger in the backseat and determine whether or not they’re wearing their seat belt. The system then lights a dash indicator and sounds an audible alarm when either of these conditions is met. Suppose you’re driving with everyone fastened, but your seatbelt warning light is still on. In that case, it’s likely because of a problem such as cargo on the seats, bad occupancy sensors, or a faulty connection to the vehicle’s supplemental restraint system.
A rear seat belt reminder is one of the most requested vehicle features by IIHS and HLDI members. However, detecting unbuckled passengers can be complicated because the seats don’t have occupancy sensors like those in the front seats. For this reason, the IIHS and HLDI suggest that regulators require rear seat belt reminders in vehicles to help address the problem.
In addition to urging vehicle manufacturers to install such devices, NHTSA is considering requirements for enhanced warnings of unfastened seat belts in the front and rear seats. Such warnings could include visual alerts that are more comprehensive and longer-lasting than the minimum FMVSS No. 208 requirement for the driver’s seat belt warning, and they could have an audio component beyond the minimum FMVSS No. 208 requirements for the front outboard rear seat warning.
However, NHTSA has received some concerns that more intrusive warnings can be annoying and lead to frustration among occupants that can desensitize or even cause them to deactivate the warnings. NHTSA is seeking comments on specifications that would maximize effectiveness without causing problems.
It Alerts Drivers to Unfastened Seat Belts
Modern vehicle systems use a combination of sensors and weight detection to determine whether occupants are wearing seat belts. These data are then input to a computer which can trigger a variety of warning signals, including dashboard lights and audible alerts. The current federal regulations require that a short-duration visual and audio warning be activated when a front seat is not fastened in passenger cars and most light-duty trucks, MPVs, and buses.
NHTSA proposes extending these requirements to rear seats to encourage seat belt use among all passengers. The proposal would require an audiovisual warning upon ignition engagement (irrespective of whether the engine is running) lasting at least four seconds to alert the driver that rear seats are not fastened and a second, longer-duration change-of-status warning whenever any seat belt experiences a status transition at speeds or distance thresholds specified in the rule.
The first-level warning would not require an accompanying audio signal, while the second-level requirement does mandate it. NHTSA is also considering ways to improve the warnings, such as adjusting their duration and other features.
One commenter recommended delaying the warning until the driver shifts the vehicle into drive mode. However, NHTSA tentatively believes that such an approach would be counterproductive and annoy drivers to the point of diminishing their acceptance of the system.
It Encourages Drivers to Fasten Seat Belts
Seat belts are effective at reducing the risk of death and injury for front and rear seat occupants in most crash modes.
Various seat belt reminder system designs are available for passenger cars, vans, and light trucks. These range from the simple systems that use a visual display to the more complex systems that utilize occupant detection.
A key issue for the rear seat belt warning system is where to locate the warning signal and whom it should warn. It can be located in the vehicle dashboard to alert the driver that a rear seat occupant is unbuckled, which leaves it up to the driver to request that they buckle up, or it can warn both the driver and the rear passenger(s) to avoid confusion.
It Deters Drivers from Driving Without Seat Belts
Seat belts help reduce injuries in a crash by slowing people down so the vehicle’s crash zone can control them. They also keep unbelted occupants from being thrown forward or into the front seat, which could increase their risk of injury.
The seatbelt warning light shows whether the seat belt is in use or not, and it will turn on if you still need to fasten it. However, if the seatbelt buckle is dirty or has broken or come loose, the signal cannot work properly, and the warning light won’t be turned on. To clean a dirty buckle, spray it with an electrical contact cleaner and connect and disconnect the seatbelt a few times to reset the circuit.
The proposal would also include a minimum audible warning that lasts for four to eight seconds on vehicle startup and remains active until all occupants are buckled. It would replace a statutory limit of the maximum audible duration established in 1974 under FMVSS No. 208.
