Herr Tilman Spingler
Robert Bosch GmbH
Dear Herr Spingler:
This is in reply to your FAX of "6/5/1997" with respect to the visual/optical headlamp aiming provisions of Federal Motor Vehicle Safety Standard No. 108. I regret that it has taken so long to get back to you with an answer.
Specifically, you "would like to know whether it is permitted to install on one side of the vehicle a headlamp with VHAD (onboard aiming) for vertical aim and on the opposite side a visually aimable headlamp in the case when a vehicle manufacturer wants to change from VHAD-headlamps to visually aimable headlamps during the production period of a certain vehicle type."
A mixed installation of this nature is not permissible. Paragraph S7.1 of Standard No. 108 requires a motor vehicle, other than a motorcycle, to "be equipped with a headlighting system designed to conform to the requirements of S7.3, S7.4, S7.5 or S7.6." (emphasis supplied). Paragraph S7.8.5 states that "When a headlamp system is installed on a motor vehicle, it shall be aimable with at least one of the following: . . ., an on-vehicle headlamp aiming device installed by the vehicle or lamp manufacturer, as specified in S22.214.171.124; or by visual/optical means, as specified in S126.96.36.199." (emphasis supplied). In these paragraphs, the standard does not refer to individual headlamps but to a "system." In our opinion, the use of the word "system" means that all headlamps within a headlighting system must comply with the same set of requirements, including its aiming features. This means that the aiming system must be identical for each headlamp in a system. For example, if one headlamp has a VHAD and is also optically/visually aimable, all headlamps in the system must have a VHAD and be optically/visually aimable.
In addition, the headlighting scheme described in your letter would not be permissible because the VHAD on the headlamp that is not visually/optically aimable appears to allow for vertical aim only and does not include a horizontal aiming feature as required by S188.8.131.52.
This interpretation requiring identical headlamps on both sides of a vehicle also ensures that all headlamps in a headlighting system on a new vehicle are designed to comply with the same photometrics.
Acting Chief Counsel