Interpretation ID: nht73-2.42

DATE: 02/09/73

FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA

TO: Alfred Teves GMBH

COPYEE: PAUL UTANS; VINSON; LIMPERT; DRIVER

TITLE: FMVSS INTERPRETATION

TEXT: Mr. Paul Utans has asked us to provide you with an interpretation of paragraph S5.3.3 of Motor Vehicle Safety Standard No. 105a, Hydraulic Brake Systems, Mr. Utans asks for confirmation of his understanding

"that the indicator lamp shall remain activated ther without the application of any pedal force or with one application of a pedal force (with a range of 25 or 50 pounds, as the case may be) if a failure of the kind described in S5.3.1(a) to S5.3.1(c) exists in the service brake system."

This interpretation is only partially correct. Paragraph S5.3.3 states in pertinent part:

". . . each indicator lamp, once activated, shall remain activated as long as the condition exists, whenever the ignition switch is in the 'on' position. An indicator lamp activated when the ignition switch is truned to the 'start' position shall be deactivated upon return of the switch to the 'on' . . . position . . . unless a failure of the kind described in S5.3.1(a) to S5.3.1(c) exists in the service brake system."

Paragraph S5.3.1(a) allows a brake pressure failure to be initially indicated either before or upon application of pedal force, but thereafter the light must remain activated while the ignition switch is in the "on" position. However, if the failure is present when the vehicle is first started, the indicator lamp must immediately be activated before any application of Pedal force, until the failure condition no longer exists.

This interpretation is subject to modification by response to petitions or reconsideration of Standard No. 105a, scheduled for publication around May 1, 1973.