Editing Seat belt (section)

===U.S. regulation history===

The [[FMVSS 208|Federal Motor Vehicle Safety Standard No. 208]] (FMVSS 208) was amended by the NHTSA to require a seat belt/starter interlock system to prevent passenger cars from being started with an unbelted front-seat occupant. This mandate applied to passenger cars built after August 1973, i.e., starting with the 1974 [[model year]]. The specifications required the system to permit the car to be started only if the belt of an occupied seat were fastened after the occupant sat down, so pre-buckling the belts would not defeat the system.<ref>{{cite AV media |url=https://www.youtube.com/watch?v=3xXtmlSHtIQ |archive-url= https://ghostarchive.org/varchive/youtube/20211211/3xXtmlSHtIQ| archive-date=2021-12-11 |url-status=live |title=Chrysler Master Technician Service Conference Session - 1974, Volume 74-1 Seat Belt Starter Interlock |date=6 April 2012 |via=YouTube}}{{cbignore}}</ref><ref name="Federal">{{Cite web |url=https://www.federalregister.gov/articles/2010/06/29/2010-15773/federal-motor-vehicle-safety-standards-occupant-crash-protection#table_of_contents|title=Federal Motor Vehicle Safety Standards; Occupant Crash Protection |date=2010}}</ref>

The interlock systems used logic modules complex enough to require special diagnostic computers, and were not entirely dependable—an override button was provided under the hood of equipped cars, permitting one (but only one) "free" starting attempt each time it was pressed.<ref name='Petersen'>{{cite book |last1=Petersen Publishing |title=The Petersen Automotive Troubleshooting & Repair Manual |chapter=Restraint Systems |editor1=Erwin M. Rosen |publisher= Grosset & Dunlap |year=1975 |location=New York, NY |pages=373–374 |isbn=0-448-11946-3}}</ref> However, the interlock system spurred severe backlash from an American public who largely rejected seat belts. In 1974, Congress acted to prohibit NHTSA from requiring or permitting a system that prevents a vehicle from starting or operating with an unbelted occupant, or that gives an audible warning of an unfastened belt for more than 8 seconds after the ignition is turned on.<ref name=Federal/><ref>{{Cite news |last=Times |first=Walter Rugaber Special to The New York |date=1974-10-16 |title=Congress Clears Auto Safety Measure Eliminating Seat Belt Interlock System |language=en-US |work=The New York Times |url=https://www.nytimes.com/1974/10/16/archives/congress-clears-auto-safety-measure-eliminating-seat-belt-interlock.html |issn=0362-4331}}</ref> This prohibition took effect on 27 October 1974, shortly after the 1975 model year began.<ref>{{cite web |url=http://www.gpo.gov/fdsys/pkg/USCODE-2013-title49/html/USCODE-2013-title49-subtitleVI-partA-chap301-subchapII-sec30124.htm |title=U.S.C. 30124 - Transportation |website=www.gpo.gov }}</ref>

In response to the Congressional action, NHTSA once again amended FMVSS 208, requiring vehicles to come with a seat belt reminder system that gives an audible signal for 4 to 8 seconds and a warning light for at least 60 seconds after the ignition is turned on if the driver's seat belt is not fastened.<ref name="Federal" /> This is called a seat belt reminder (SBR) system. In the mid-1990s, the Swedish insurance company [[Folksam]] worked with Saab and Ford to determine the requirements for the most efficient seat belt reminder. One characteristic of the optimal SBR, according to the research, is that the audible warning becomes increasingly penetrating the longer the seat belt remains unfastened.<ref name="SWOV">{{cite web |title=SWOV Fact sheet |year=2014 |url=http://www.swov.nl/rapport/Factsheets/UK/FS_Seatbelt_reminders.pdf |access-date=2015-04-29 |url-status=dead |archive-date=2015-06-17 |archive-url= https://web.archive.org/web/20150617081622/http://www.swov.nl/rapport/Factsheets/UK/FS_Seatbelt_reminders.pdf}}</ref>