Interpretation ID: nht91-5.22

DATE: August 12, 1991

FROM: John E. Calow -- Oshkosh Truck Corporation, Chassis Division

TO: Taylor Vincon -- Legal Council, NHTSA

TITLE: None

ATTACHMT: Attached to letter dated 9-18-91 from Paul Jackson Rice to John E. Calow (A38; Std. 108)

TEXT:

Quite a while ago I spoke with you about optically combined Brake Lights and Hazard Warning Lights. Per our conversation I understood that the Brake Lights would over-ride the Hazard Warning Lights if both were activated. Recently it was brought to my attention that my interpretation was in error. Thus, I am requesting that you review following questions and submit a written verification.

1) If the Brake Lights and Hazard Warning Lights are optically combined and both are activated (per federal regulations) which of the following will occur? A) The brake lights will over-ride causing a steady light emission. B) The hazard lights will over-ride causing a flashing light emission.

2) If the vehicle has a Center High Mounted Stop Lamp "CHMSL" is it acceptable to have the Hazard Warning Lights over-ride the Brake Lights if the CHMSL has a steady light emitance upon brake application?

Please send the written verification to my attention. Our address is on my enclosed business card.

Thank you for your time and consideration, if you have any questions please feel free to contact me.