working horn requirement

https://aged-wiki.win/index.php/How_to_Test_Brake_Lights_Safely_and_Diagnose_Common_Issues

The working horn requirement often involves testing and verifying that the horn produces a sound level of at least 110 decibels at a distance of a foot, ensuring it functions reliably in all weather conditions without damaging the driver's hearing, and that its wiring and mounting are secure against vehicle vibrations.