Interpretation ID: 77-4.21

TYPE: INTERPRETATION-NHTSA

DATE: 10/18/77

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Lucas Industries North America, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: In response to your letter of August 19, 1977, we advise you that your mistake in referencing S4.5.2 of Standard No. 108 instead of S4.5.1 in your earlier letter of May 13, 1977, does not alter our previous interpretation of June 16, 1977.

Your design appears to meet the specifications of J564a allowing compliance of the headlamp beam switching system with S4.5.1 when installed in a motor vehicle.

YOURS TRULY,

AUGUST 19, 1977

Ref NOA-30

Joseph J Levin, Jr Chief Counsel U.S. Department of Transportation National Highway Traffic Safety Administration

Subject Lucas 21SA Headlamp Switch Circuit

We thank you for your opinion on the subject switch circuitry that we requested in our letter dated May 13, 1977.

Inadvertently, we had referred to section S4.5.2 of Federal Motor Vehicle Safety Standards 108 when requesting your help, instead of section S4.5.1 of standard 108.

Section S4.5.1 referes to the SAE recommended practice J564a "Headlamp Beam Switching" and it is part 4 of this standard which we are primarily concerned with, that is, "the switch shall be designed so that the headlight circuits are never maintained open" (The absence of a dead spot).

We again submit the wiring circuitry for the subject headlamp switch and ask that you re-evaluate this circuit as per section S4.5.1 and forward your opinion to us.

Eric E Gough Staff Assistant (Technical)

cc: K. J. JONES 21SA HEADLAMP BEAM SWITCH CIRCUIT

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JUN 16 1977

Eric E. Gough Staff Assistant (Technical) Lucas Industries North America, Inc.

DEAR MR. GOUGH:

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,

Joseph J. Levin, Jr. Chief Counsel

cc: MR. VINSON; MR. CARTER

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.

LUCAS INDUSTRIES NORTH AMERICA INC

Eric E Gough Staff Assistant (Technical)

ENC

21SA HEADLAMP BEAM SWITCH CIRCUIT

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b) LUCAS 21SA SHY DIP BEAM --> MAIN BEAM

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