Interpretation ID: 18897-3.wkm
Phillip A. Proger, Esq.
Jones, Day, Reavis & Pogue
Metropolitan Square
1450 G Street, NW
Washington, DC 20005-2088
Dear Mr. Proger:
This refers to your meeting with Messrs. Daniel, Myers, and Woods of this agency on October 1, 1998, and your letter of October 8, 1998,(1) in which you asked whether it was permissible to deactivate momentarily the antilock brake system (ABS) malfunction indicator lamp (MIL) following a bulb check for an ABS diagnostic test. The answer is no.
Your letter stated that Lucas Varity Light Vehicle Braking Systems (LVBS) desires to perform an ABS diagnostic test immediately following the bulb check, thereby deactivating the MIL momentarily. Following this momentary deactivation, the lamp would again illuminate if a malfunction message existed in the system. You stated that one or more of your diagnostic tests would seek to determine whether a short circuit existed in the system which may inadvertently activate the MIL, and that other unspecified tests cannot be performed while the lamp is activated. You stated that a momentary deactivation of the MIL following the bulb check would be beneficial and consistent with the overall purpose of the lamp activation protocol of Federal Motor Vehicle Safety Standard (Standard) No. 105, Hydraulic and electric brake systems, as amended.(2)
Paragraph S5.3 of Standard No. 105 requires each vehicle to which the standard applies to have a brake system indicator lamp or lamps that meet the requirements of S5.3.1 through S5.3.5. Vehicles with a gross vehicle weight rating (GVWR) of 10,000 pounds or less may have a single brake system indicator lamp, while vehicles with GVWRs greater than 10,000 pounds must have a separate indicator lamp for ABS malfunction. Further, vehicles with GVWRs greater than 10,000 pounds are required by S5.3.3(b) to store a malfunction message in the ABS after the ignition switch is turned to the "off" position so that the MIL is automatically reactivated when the ignition switch is again turned to the "on" position. The MIL must also be activated during the check of lamp function, or "bulb check," whenever the ignition switch is turned to the "on" position, and deactivated at the end of the bulb check unless a malfunction is present or a malfunction message exists from the previous ignition cycle. Thus, after the check of lamp function, if a malfunction message exists, the MIL must remain illuminated after the other indicator lamps deactivate. No deactivation of the MIL at that point, however "momentary," is permitted by the standard. Permitting the MIL to extinguish, even "momentarily," would defeat the purpose of the requirement and could be confusing to drivers and inspectors.
I hope this information is helpful to you. Should you have any questions or have need any additional information, feel free to contact Mr. Myers at this address or at (202) 366-2992, or fax at (202) 366-3820.
Sincerely,
Frank Seales, Jr.
Chief Counsel
Ref:105
d.5/14/99
1. We note that you sent us three letters dated October 8, 1998, all referring to the October 1, 1998 meeting and all relating to the malfunction indicator lamp protocol of Standard No. 105. We are responding to the three letters separately.
2. With the exception of paragraph S5.3.3(b), the amendments to Standard No. 105 at issue here entered into effect on March 1, 1999. The compliance date of the requirements of S5.3.3(b) was extended until September 1, 1999 by Interim Final Rule, Request for Comments dated February 26, 1999 (64 FR 9446).