Analysis by Daniel Stern
VW will recall over 160,000 vehicles in the U.S. market because their headlamps can be aim-adjusted horizontally as well as vertically: a horizontal adjuster screw blockoff cap may not have been installed on one or both headlights, of about 116,000 Atlases and 547,000 Passats.
Dealers will check the headlamps and install missing aim adjuster blockoff caps as necessary, starting once the customer notification begins this month.
As required by U.S. law, VW submitted a report to NHTSA on 6 June, acknowledging the defect. The nominal reason for the safety recall: Incorrectly adjusted headlights may result in reduced visibility for the driver and other motorists, which could increase the risk of a crash.
Since the late 1990s, most American-spec headlamps are not horizontally aimable. They’re not allowed to be, unless they’re equipped with an onboard calibrated horizontal aim indicator or another type of device allowing the headlamp aim to be adjusted without reference to the light beam itself. As such devices add cost, virtually all automakers choose the equally legal alternative: no device, no cost, and no horizontal aimability. This state of affairs dates back to the mid-1990s regulatory negotiation that resulted in U.S. headlamps that could be aimed by visual or optical reference to the light beam. The dual rationale that arose from that negotiation for this aspect of the regulation: visual/optical-aim headlamps would not need horizontal aimability because they would have a wide high-intensity zone making horizontal aim unimportant to the lamps’ safety performance, and there’s no way to provide for visual/optical horizontal aimability without damaging the beam pattern.
Time has not been kind to these assertions: Normal bumps and knocks and car park taps, auto body repairs and headlamp replacements did not stop sending the effective horizontal aim wrong. And two of the things IIHS headlight performance tests have shown is that vehicles can and do come off the assembly line with incorrect horizontal headlamp aim—and it matters quite a lot to seeing and glare. And the notion that visual/optical horizontal aim is impossible without degrading the beam is difficult to reconcile with the rest of the world’s long history of doing it on every vehicle with fine success under European and Japanese regulations since the 1950s.
Perhaps a more realistic reason parties to the negotiation were keen to eliminate horizontal aimability was the perceived opportunity to take cost out of headlamps by simplifying the mount/aim hardware. But lighting hardware grew a great deal more international shortly after the new regulations took effect, and the rest of the world still requires horizontal aimability, so we find ourselves in a situation where makers provide H-aim hardware and then block or disable it for the American market—more cost, not less.
What’s more, adaptive headlamps—particularly ADB—must have horizontal aimability; even if the idea that a wide high-intensity zone makes H-aim unimportant had merit, it doesn’t apply to lamps designed and intended to dynamically create and modulate precise, accurate cutoffs between closely adjacent horizontal angles. Several commenters to NHTSA’s ADB proposal mentioned this urgent need. Who knows whether horizontal aimability will come to American headlamp regs. In the mean time, we have the mind-bending situation that in the world’s № 2 auto market, the presence of a demonstrably needed safety provision is considered an illegal “safety defect”.
