Most signal and marking lighting devices have light sources (bulbs), which can be based on either filament or LED technology. To assure field replacement, it is important that light source types employed be readily available in normal service channels. This document defines the physical, electrical, and photometric characteristics necessary to achieve a proper replacement for popular types of signal and marking light sources.
Some of the design characteristics in this document are listed solely for the sake of standardization and are not intended to describe the performance of lighting devices (lamp assemblies) on the vehicle.
This standard was revised in two aspects. Specification for recent new signal and marking filament light sources have been included. The sections that were added/revised as part of the filament light source update are listed below. In addition to that the scope is extended to include solid state lighting.
Due to the development of more efficient and cost-effective solid-state lighting solutions using light emitting diodes (LEDs) over the last years, the use of solid-state lighting options for signaling and lighting function in vehicles has become more and more common. In many applications the installed light sources are sealed system solutions, where customized LED arrays and associated electronics are used. Another option for solid-state lighting is the use of replaceable LED light sources, which can be inserted into a system using traditional socket systems and can therefore be easily exchanged. This principle is similar to currently existing miniature filament bulbs. This proposal is intended to extend the scope of SAE J573 to include these replaceable LED light sources in a similar manner to filament light sources. Due to differences between LED light sources compared to filament light sources in terms of the optical, mechanical and electronic characteristics, the LED light sources are not intended as direct replacement of filament light sources.