Interpretation ID: 2780y
President, Hella Inc.
P.O. Box 1064
Cranford, NJ 07016
Dear Mr. Williams:
This is in reply to your letters of November 1 and 8 to Richard Van Iderstine of this agency.
In your letter of November 1 you ask "How would NHTSA view the addition of a rear spoiler with integrated third rear brake light to a vehicle already originally equipped with a third rear brake light?"
There are two relevant provisions of Standard No. 108 that deal with your question. The first is relevant if installation of the spoiler prevents the original lamp from meeting the photometric or visibility requirements of Standard No. l08. If this occurs, compliance may be maintained by installing another center high-mounted lamp that meets all requirements of Standard No. l08. See S5.3.1.1. Presumably, the lamp in the spoiler is designed, or could be designed, to comply to all applicable requirements.
A further question is whether two center high-mounted stop lamps are permissible. An auxiliary lamp is prohibited by S5.1.3 if it impairs the effectiveness of the lighting equipment required by Standard No. l08. One example of impairment is when the auxiliary lamp creates confusion as to the function of the original lamp. The motoring public is used to seeing only one center lamp in operation. Although we cannot reach a definitive conclusion that an auxiliary center stop lamp would impair the effectiveness of the original center stop lamp, it would probably be prudent to ensure that there is only one center stop lamp in operation. Thus, if the spoiler lamp complies with Standard No. l08, the original lamp may be disconnected. If the spoiler lamp does not comply with Standard No. l08 and the original lamp remains in compliance with Standard No. 108, the question of impairment arises. On balance, it would appear unlikely that impairment would result from this configuration.
In your letter of November 8 you ask several questions with respect to the installation of center high-mounted stop lamps on pickup trucks. On May 31, l990, NHTSA proposed that the lamp be installed on pickup trucks and some other types of vehicles as well. We anticipate publishing a final rule on this issue in the Federal Register in the near future. The preamble to the rule will address your questions on location of the lamp.
Sincerely,
Paul Jackson Rice Chief Counsel
ref:l08 d:12/24/90