Interpretation ID: 77-3.3

TYPE: INTERPRETATION-NHTSA

DATE: 06/16/77

FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA

TO: Lucas Industries North America, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of May 13, 1977, to the Administrator asking whether the circuitry diagram that you enclosed would allow compliance with S4.5.2 of Federal Motor Vehicle Safety Standard No. 108.

Paragraph S4.5.2 requires that "each vehicle shall have a means for indicating to the driver when the upper beams of the headlamps are on that conforms to SAE Recommended Practice J564a, April 1964 . . . ." Your diagram appears to meet the specifications of J564a allowing compliance of the system with S4.5.2 when installed in a motor vehicle. The entity legally responsible for compliance with S4.5.2, of course, is the vehicle manufacturer who must certify that its products meet all applicable Federal motor vehicle safety standards.

YOURS TRULY,

Lucas Industries North America Inc

MAY 13, 1977

The Administrator National Highway Traffic Safety Administration

Our sister company in Birmingham England, Lucas Electrical Limited, requests clarification of Section 4.5.2 of Standard 108 - Lamps, Reflective Devices and Associated Equipment - and SAE Recommended Practice J564, which is referenced in Standard 108, Section 4.5.2.

We submit a diagram of a four headlamp installation in which a Lucas Model 21SA switch and a normally closed relay is used to ensure that the headlight circuits cannot be held in the open condition. Manual and auto reset switches are also included in the circuit to ensure correct circuit operation. We are also submitting traces showing the transient voltage conditions when switching from:

a) Main beam to dip beam

b) Dip beam to main beam

This circuitry we have developed allows, as far as we are aware, for us to comply with Section 4.5.2 of Standard 108. We look forward to receiving whatever comments you deem applicable and will be pleased to supply additional material if you so desire.

Eric E Gough Staff Assistant (Technical) 21SA HEADLAMP BEAM SWITCH CIRCUIT

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