Rationale: This Standard has been fully revised to include improved visual/optical aim requirements, restructured to improve flow, understanding and usability. Additionally, all graphics were updated.
SAE J599 has been the primary reference document for headlamp and fog lamp aim information for many years. Last revised in 1997, it was due for reconsideration in 2002. Revisions to FMVSS-108 which allowed an alternative beam pattern, specifically Visual Optical Aim (VOA) type headlamps, made SAE J599 obsolete just a year after its publication, however
The allowance for VOA was intended to improve the consistency and repeatability of headlamp aim. With the traditional SAE beam pattern, proper aiming was difficult if no aiming equipment was available to use. The visual techniques outlined in SAE J599 were certainly adequate, but the attributes of the beam patterns and the difficulties of obtaining a totally dark environment when on a level surface limited repeatability significantly. The more distinct cutoff of a VOA pattern greatly enhances repeatability and theoretically will reduce the chance of misaim.
The differences between VOA beam patterns and traditional SAE beam patterns is substantial, however, and the procedures outlined in the 1997 version of J599 simply cannot be applied to VOA lamps. The American Association of Motor Vehicle Administrators (AAMVA) apparently recognized this fact after updating their Vehicle Inspection Handbook for 1999. They issued a memorandum to clarify how VOA lamps should be inspected and to what audit criteria they should be held. Their proposals were basically modifications on the existing J599. Unfortunately, the tolerances used by the AAMVA did not necessarily mesh with all VOA beam patterns, especially for horizontal aim inspection. This revision addressed these disparities by balancing the NHTSA rulemaking with the existing SAE J599 and the AAMVA memorandum.
The result was the deletion of the requirement to audit horizontal aim. In some ways, this seems extreme in that it theoretically allows lamps to be misaimed horizontally by an outrageous amount (say 20º). In fact, however, there is no disputing that “no requirement” is the only requirement which we can make. Since the VOA beam patterns in the USA are not required to have a visual cue for horizontal aim, there is no way to determine where such a lamp is aimed. Furthermore, if for some reason there is a visual cue in the pattern, it is not necessary for that cue to be at the VV line of the beam pattern. The “elbow”, “kink” or “z-step” in the pattern could be to the left or right of VV by design, as long as the lamp still meets the requirements of FMVSS-108.
In addition to addressing the advent of VOA headlamps, some other updates were made. All of the definitions were reexamined based on all existing SAE documents. Only those definitions unique to this document are retained. Throughout the document, some sentences were reworded and/or paragraphs were realigned to help clarify their intent. This was done with the hopes that individuals who are not familiar with automotive lighting would still be able to properly perform the aiming or aim inspection processes.
Included in: Ground Vehicle Lighting Subscription Learn More