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09-002608 403&404

Harry C. Gough

Vehicle Modification Engineer

Easter Seals Connecticut Mobility Center

158 State St.

Meriden, CT 06450

Dear Mr. Gough:

This letter responds to your request for an interpretation of the threshold warning signal requirement of S6.1 and the associated testing procedure in S7.4 of Federal Motor Vehicle Safety Standard (FMVSS) No. 403 (Standard 403), Platform Lift Systems For Motor Vehicles. See

49 C.F.R.  571.403.

You describe a particular Braun lift model in which the platform is stored under the vehicles floor. When the lift is deployed, the platform is extended out from underneath the vehicle approximately 12 inches below the level of the floor and then is brought upward to come to the floor level. You observed that, if the platform is only partially deployed, the threshold warning system is not activated and that it is only activated after the platform initially reaches floor level. You note that in the preamble to the final rule, the agency adopted the threshold warning requirement because of the risk involved in backing off a vehicle when the lift is not properly positioned. You acknowledge that the wheelchair lift design that you describe would not fail the compliance test procedure set forth in S7.4.2 of Standard 403, but ask whether the design is consistent with the intent of the threshold warning system.

By way of background, the agency established Standard 403 in order to protect individuals who are aided by canes, walkers, wheelchairs, scooters, and other mobility devices and rely on platform lifts to enter/exit a motor vehicle. Standard 403 is an equipment standard that specifies minimum performance requirements for platform lifts designed for installation on motor vehicles.

We read your letter as asking the general question of whether Standard 403 requires the threshold warning system to be activated before a lift is fully deployed. We interpret S6.1 to require that the threshold warning signal activate only after the lift has been fully deployed. Our interpretation is supported by the testing procedure set forth in S7.4.2. The testing procedure requires that the lift platform be maneuvered to the vehicle floor loading position before the test device is placed in the threshold area. Accordingly, we do not interpret S6.1 to require the threshold warning system to be activated before the lift is fully deployed.

I hope this information is helpful. If you have any further questions, please feel free to contact David Jasinski of my office at (202) 366-2992.


O. Kevin Vincent

Chief Counsel

Dated: 7/19/2010