NHTSA announces minor TPMS rule changes

Sept. 7, 2005

The National Highway Traffic Safety Administration (NHTSA) is postponing the compliance date for inclusion of required language regarding tire pressure monitoring systems (TPMS) in vehicle owners' manuals to Sept. 1, 2006, among several other changes to facets of its TPMS rule.

"We do not believe that extending the compliance date in this manner would result in any safety consequences," say NHTSA officials.

"Delay of the owner's manual requirements would not impact the functioning of the TPMS or the warnings that it provides, and we expect that even before that date, TPMS-equipped vehicles would have some owner's manual statement presenting relevant information to the consumer.

"We specifically note that delay in the compliance date for the

standard's owner's manual requirements does not impact vehicle

manufacturers' responsibility to provide (tire pressure monitoring systems) complying with FMVSS No. 138 on a schedule consistent with the phase-in commencing on Oct. 5, 2005, as set forth in the April 8, 2005, final rule."

The decision is in response to petitions made to NHTSA.

Also as the result of petitions, NHTSA has decided to retain the final rule's requirement that the TPMS indicator lamp "illuminate whenever there is a malfunction that affects the generation of transmission of control or response signals in the vehicle's tire pressure monitoring system.

"However, in response to petitions, we have decided to amend the standard's test procedures for malfunction detection to clarify that telltale lamps will not be disconnected, because such malfunctions will be indicated during the bulb check(s) required under the standard."

NHTSA is amending regulatory wording "to clarify that for a combined low tire pressure/TPMS malfunction indicator telltale, the same flashing/continuous illumination sequence is required for one or more malfunctions that may affect the system simultaneously."

In other changes, NHTSA is reducing the standard's test procedures from a two psi pressure adjustment to one psi.

"The two psi adjustment was intended to facilitate testing, but several petitioners expressed concern that (it) could allow (systems) to achieve compliance with an under-inflation detection capability of 30% or more.

"The agency anticipates that a one psi adjustment would continue to facilitate testing while maintaining the under-inflation level close to the standard's 25% under-inflation activation threshold.

"In order to more clearly differentiate between the TPMS

standard's two phase-in production periods which are of different

lengths (i.e., almost 11 months vs. one year), we have decided to

modify 49 CFR 585.66, Reporting Requirements, to differentiate the

reports to be submitted to the agency for each of the two phase-in

periods. As currently drafted, section 585.66(b)(1), Basis for

Statement of Compliance, and section 585.66(b)(2), Production, require manufacturers to report values for the full production year, without mention of the period corresponding to the first period of the phase-in (i.e., from Oct. 5, 2005, to Sept. 1, 2006), which is the relevant total production value for calculation under S7.1(b) of FMVSS No. 138.

"Because the reporting of this information directly relates to

determining compliance with the requirements of FMVSS No. 138, we have decided to revise 49 CFR 585.66(b)(1) and (2) to clearly differentiate between the two phase-in production periods."