Interpretation ID: nht87-2.47

TYPE: INTERPRETATION-NHTSA

DATE: 07/13/87

FROM: AUTHOR UNAVAILABLE; SIGNATURE UNAVAILABLE; NHTSA

TO: Mr. Yueh-An Chen

TITLE: FMVSS INTERPRETATION

TEXT:

Mr. Yueh-An Chen Division Head Planning Division Yue Loong Motor Engineering Center P.O. Box 510 Taoyuan, Taiwan Republic of China

Dear Mr. Chen:

This is in reply to your letter of June 5, 1987, asking whether certain rear lighting arrangements are acceptable under Federal Motor Vehicle Safety Standard No. 108.

You have submitted a diagram showing four lamps on either side of the vertical centerline of the rear of the car. The most inboard lamps, denoted "R", are the backup lamp system. Yue Loong contemplates four different functions for the remaining three sys tems of lamps, "A", "B", "C", and "D", "E", "F" (inboard to outboard) and asks about acceptability.

1. In the first system, ABC or DEF will serve the respective turn signal functions. All lamps would serve as hazard warning signal lamps and stop lamps. Standard No. 108 generally does not prohibit lamp clusters from performing multiple functions. This s ystem is permissible as long as ABC and DEF meet all Standard No. 108's requirements for turn, hazard warning, and stop signals when tested in those modes. Your diagram, however, does not indicate which, if any, of these lamps provide the taillamp functi on that Standard No. 108 also requires for the rear of motor vehicles. Therefore, lamps ABC and DEF would have to meet the taillamp requirements as well.

2. The second system differs from the first in that the hazard warning system would not operate through all six lamps of the turn signal system, but only through the two most outboard lamps. This system is permissible, as Standard No. 108 does nor mandat e use of all turn signal lamps for the hazard warning signal mode, requiring only "at least one" on each side of the vehicle, front and rear.

3. The third system differs from the second in that the two most outboard lamps would no longer be part of the stop lamp system. We view this arrangement as permissible. Standard No. 108 requires that stop lamps, turn signal lamps, and taillamps be locat ed "as far apart as practicable". In a literal sense this would appear to require stacking the lamps vertically at the outboard edges of the vehicle, but NHTSA has not adopted a design-restrictive interpretation of this requirement. The determination of practicability is initially that of the manufacturer, but it is subject to review and comment by this agency in instances where such a determination appears clearly erroneous. Where the turn signal system (or part of it) is located at the outboard edges of the vehicle, and the stop lamps and taillamps are adjacent to it, or to each other, we view the "practicability" requirement as met.

4. The fourth system differs from the third in that the stop lamp system would be either that of the systems discussed in items 2 and 3 above, and operating according to Section 3 of your letter. Either system would be acceptable, subject to the operatio nal restriction with turn signal lamps that I shall discuss in my response to Section 3.

Next, you have presented four kinds of flashing arrangements for the turn signal lamps. You ask (a) which could meet Standard No. 108, and (b) which could meet Standard No. 108 assuming a flash cycle of 1-4 seconds. With respect to (a), all four would ap pear to be acceptable. The standard allows multiple turn signal lamps either to flash simultaneously, or sequentially in the direction of the turn. With respect to (b), Standard No. 108 specifies that a turn signal flasher provide not less than 60 and no t more than 120 cycles per minute. This translates to not less than 1 and not more than 2 cycles per second. This requirement would have to be met by all lamps in arrangement i.e. where all lamps operate simultaneously. When operating sequentially, each lamp individually would be subject to the restrictions with the result that the inclusive cycle for a three lamp system would be not less than 3 seconds and not more than 6 seconds. Therefore, arrangements (a), (b), and (c) would meet this requirement as suming a flash cycle of 4 seconds, but arrangement (d) would not, being restricted to a cycle of 2 seconds maximum.

In your third question, or Section 3 as you term it, you have combined the conditions of your first two questions and attached a table of "detailed operating states" of the rear lamps, which incorporates three attached figures, with the question whether it would comply with Standard No. 108. Two of the Operating States illustrated denote the stop lamp "on" and, individually, the right or left turn signal as "on". Standard No. 108 does not allow simultaneous activation of the stop lamp and turn signal la mp when the stop signal is optically combined with the turn signal, In that event, the circuit must be such that the stop signal cannot be turned on in the turn signal which is flashing (paragraph 4.2, SAE Standard J586c Stop Lamps, August 1970, incorpor ated by reference in Standard No. 108). Our other comment concerns "Fig. a", "Fig. b", and "Fig. c" depicting flash cycles of the turn signal lamp;. As we noted earlier, the individual lamps are subject to the cycle minima and maxima of 1 to 2 cycles per second, and none of the rates depicted in the three Figures appears to meet the minimum requirement of 1 second. Otherwise, the "Operating State" table appears acceptable.

I hope that this answers your questions.

Sincerely,

Erika Z. Jones Chief Counsel

June 5, 1987

Ms. Erika Z. Jones Chief Counsel U.S. Department of Transportation National Highway Traffic Safety Administration 400 Seventh St., S.W. Washington, D.C. 20590

Dear Mr. Jones,

On Jan. 23, 1986 we consulted NHTSA about the problems of headlamps systems, and received your reply letter of May. 8, 1986. The information was very useful to us, thank you again for your kind assistance.

Now, we still have some questions about the turn signal lamps and other rear lamps, will you please kindly give us your suggestions as soon as possible?

The feature of rear lamps of the vehicle is shown as fig. 1. In the following conditions, which could meet the requirements of the FMVSS No. 108 and other related U.S.A. regulations?

1. As shown in Fig. 1, "R", is the backup lamp, and the lighting function of the other lamps "A", "B", "C", "D", "E", "F" are shown as Table 1. In the four cases, which could meet the requirements of U.S.A. regulations?

2. As shown in Fig. 2, there are four kinds of flashing arrangements for the turn signal lamps "ABC" (LH) & "DEF" (RH). a. Which could meet the requirements of U.S.A. regulations? b. If the period of flashing (t) 1 cycle = 1 - 4 sec. which could meet the requirements of U.S.A. regulations?

3. Combining the conditions of section 1, 2, we set a detailed operating state of the rear lamps as shown in Table 2. Could it meet the requirements of U.S.A. regulations?

Your kind assistance and earlier reply will be highly appreciated.

Sincerely yours,

Yueh-An Chen Division Head Planning Division SEE HARD COPY FOR GRAPHIC INFORMATION