[Federal Register Volume 61, Number 32 (Thursday, February 15, 1996)]
[Rules and Regulations]
[Pages 5949-5955]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-3382]



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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. 92-29; Notice 10]
RIN 2127-AF96


Federal Motor Vehicle Safety Standards; Stability and Control of 
Medium and Heavy Vehicles During Braking

AGENCY: National Highway Traffic Safety Administration (NHTSA), DOT.

ACTION: Final rule, petitions for reconsideration.

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SUMMARY: This document responds to petitions for reconsideration of 
final rules that amended FMVSS No. 105, Hydraulic Brake Systems, and 
FMVSS No. 121, Air Brake Systems, to require medium and heavy vehicles 
to be equipped with an antilock brake system (ABS). In response to the 
petitions, this document requires continuous power for trailer ABS 
systems, in place of the dedicated power and separate ground previously 
required, and delays the implementation date for the in-cab trailer 
malfunction indicator by four years. It also extends by three years the 
period in which exterior ABS failure indicators are required on 
trailers.

DATES: Effective Dates: The amendments to 49 CFR 571.121 are effective 
March 1, 1997.
    Compliance Dates: Compliance with the amendments to paragraphs 
S5.1.6.2(b) and S5.2.3.2 of 49 CFR 571.121 will be required on and 
after March 1, 2001. Compliance with the amendments to paragraph 
S5.1.6.3 for truck tractors will be required on and after March 1, 1997 
and for single unit vehicles will be required on and after March 1, 
1998. Compliance with the amendments to paragraph S5.2.3.2 will be 
required on and after March 1, 2001. Compliance with the amendments to 
S5.2.3.3 will be required on and after March 1, 1998.
    Petitions for Reconsideration: Any petitions for reconsideration of 
this rule must be received by NHTSA no later than April 1, 1996.

ADDRESSES: Petitions for reconsideration of this rule should refer to 
the above referenced docket numbers and should be submitted to: 
Administrator, National Highway Traffic Safety Administration, 400 
Seventh Street, SW., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT:
    For non-legal issues: Mr. Robert M. Clarke, Office of Crash 
Avoidance, National Highway Traffic Safety Administration, 400 Seventh 
Street, SW., Washington, DC 20590 (202) 366-5278.
    For legal issues: Mr. Marvin L. Shaw, NCC-20, Rulemaking Division, 
Office of Chief Counsel, National Highway Traffic Safety 
Administration, 400 Seventh Street, SW., Washington, DC 20590 (202) 
366-2992.

SUPPLEMENTARY INFORMATION:

I. Background.
II. Petitions for Reconsideration.
III. NHTSA's Decision and Analysis of Issues.
    A. Agency's Decision.
    B. Trailer Powering.
    1. Background and Previous NHTSA Rulings.
    2. Petitions for Reconsideration of December 1995 Final Rule
    3. Agency's Decision
    C. In-Cab Trailer Malfunction Indicators
    D. External Trailer Malfunction Indicators

I. Background

    Section 4012 of the Motor Carrier Act of 1991, a part of the 
Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991, P.L. 
102-240, directed the Secretary of Transportation to initiate 
rulemaking concerning methods for improving braking performance of new 
commercial motor vehicles, including truck tractors, trailers, and 
their dollies. Congress specifically directed that such a rulemaking 
examine antilock systems, means of improving brake compatibility, and 
methods of ensuring effectiveness of brake timing. The Act required 
that the rulemaking be consistent with the Motor Carrier Safety Act of 
1984 (49 U.S.C. Sec. 31136) and be carried out pursuant to, and in 
accordance with, the National Traffic and Motor Vehicle Safety Act of 
1966 (now recodified as 49 U.S.C. Sec. 30101 et seq. (Safety Act)).
    On March 10, 1995 (60 FR 13216, 60 FR 13297), NHTSA issued final 
rules that required medium and heavy vehicles 1 to be equipped 
with an antilock brake system (ABS) to improve their directional 
stability and control during braking. The March 1995 final rules also 
reinstated stopping distance requirements for air-braked heavy vehicles 
and established stopping distance requirements for hydraulic-braked 
heavy vehicles.

    \1\  Hereinafter referred to as ``heavy vehicles''
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    In addition to the ABS requirement, the ABS final rule required 
truck 

[[Page 5950]]
tractors and other towing vehicles to supply dedicated, full time 
electrical power to a trailer ABS and required truck tractors and other 
towing vehicles to be equipped with two separate in-cab lamps: one 
indicating malfunctions in the towing vehicle ABS and the other 
indicating malfunctions in the ABS on one or more towed trailers and/or 
dollies. The rule also required all trailers, including dollies, 
produced during an eight-year transition period, to be equipped with an 
external malfunction indicator. In response to petitions for 
reconsideration of these requirements, NHTSA published a final rule on 
December 13, 1995 (60 FR 63965) affirming its decision to require these 
features.

II. Petitions for Reconsideration of December 1995 Final Rule

    NHTSA received petitions for reconsideration of the December 1995 
amendments to the final rule from the American Trucking Associations 
(ATA) which represents trucking fleets, the National Private Truck 
Council (NPTC) which represents private trucking fleets, the Truck 
Manufacturers Association (TMA) 2, the Truck Trailer Manufacturers 
Association (TTMA) which represents trailer manufacturers, the Heavy 
Duty Brake Manufacturers Council (HDBMC) 3 which represents heavy 
duty brake component manufacturers, Midland-Grau, Kelsey-Hayes, 
Rockwell WABCO, Vehicle Enhancement Systems (VES), AlliedSignal, 
General Motors, Ford, and the Recreational Vehicle Industry Association 
(RVIA).4

    \2\ TMA member companies include Ford, Freightliner, General 
Motors, Mack Trucks, Navistar International, PACCAR, and Volvo GM 
Heavy Truck.
    \3\ HDBMC member companies include Abex, AlliedSignal, Eaton, 
Midland-Grau, Ferodo America, Haldex, Lucas, MGM Brakes, Motion 
Control/Carlisle, Rockwell, Rockwell WABCO, and Spicer/Dana.
    \4\ General Motors, Ford, Kelsey-Hayes, and the RVIA all address 
amendments to FMVSS No. 105. In this notice, the agency is 
responding to the issues relating to FMVSS No. 121. The agency will 
address the petitions raising FMVSS No. 105 issues in a future 
notice.
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    As did the petitioners for reconsideration of the March 1995 final 
rule, all petitioners for reconsideration of the December 1995 final 
rule agreed with and supported NHTSA's decision and schedule requiring 
all heavy vehicles to be equipped with ABS. ATA, TMA, and TTMA 
reference what they refer to as the ATA/TMA/TTMA Industry Consensus 
Position ABS Reconsideration petition,5 with which they have 
stated their concurrence. The Industry Consensus Position states that 
the agency should retain the current overall requirements and timing. 
Similarly, TMA stated that its companies ``continue to support the 
production, sale, and service of ABS within the specified time 
frames.'' Nevertheless, the Industry Consensus Position and each of the 
petitioners requested that the agency modify the requirements that 
address trailer ABS power and the in-cab trailer malfunction indicator. 
Specifically, the Industry Consensus Position is that the agency should 
(1) delete the requirement for continuous, dedicated power 6 to 
the trailer ABS and replace it with a requirement for continuous power 
but no dedicated circuit (with backup power on the stoplamp circuit) 
and delete the separate ABS ground requirement, and (2) delay the 
effective date for an in-cab trailer warning light, but specify another 
date that will accelerate the development of the specific means for 
achieving the goal of having that warning light. The petitioners 
supporting the Industry Consensus Position explained that the heavy 
vehicle manufacturers and users are working together and are committed 
to developing and deploying a satisfactory in-cab trailer warning light 
within the extended time period requested.

    \5\ Hereinafter referred to as ``Industry Consensus Position.''
    \6\ The terms continuous power, dedicated power, and connector 
are discussed in the next section.
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III. NHTSA's Decision and Analysis of Issues

    As explained below, NHTSA has decided to amend FMVSS No. 121 
consistent with the Industry Consensus Position and to replace the 
requirement for dedicated power to trailer ABS with a requirement for 
continuous power. Stoplamp power will continue to be required to 
provide back-up power for the ABS. In addition, the agency has decided 
to delete the requirement for a separate ABS ground and to allow a 
common ground for ABS trailer powering. The agency has also decided to 
delay the implemenation date for the in-cab trailer malfunction 
indicator until March 1, 2001.

A. Trailer Powering

1. Background and Previous NHTSA Rulings
    A trailer's antilock brake system may receive its electrical power 
in one of the following ways: (1) intermittent power through the 
stoplamp circuit, (2) continuous power through a circuit that is shared 
and provides power to more than one electrical component or which is 
used to transmit one or more signals, or (3) continuous, dedicated 
power through a circuit whose sole function is to provide power to the 
trailer ABS. With stoplamp powering, electrical power to the ABS is 
only supplied when the brake pedal is applied and the stop lamp switch 
is activated. As a result, the trailer ABS must share power with 
stoplamp bulbs, which decreases the voltage available for powering the 
trailer ABS. With continuous powering, electrical power to the trailer 
ABS is present at all times, but other devices could be powered off the 
same circuit and multiplexed 7 communication signals could be 
carried on the circuit. With dedicated powering, electrical power to 
the trailer ABS is present at all times, but no other device can be 
powered off this circuit and communications signals cannot be carried 
on the circuit.

    \7\ Multiplexing is defined by the Society of Automotive 
Engineers's (SAE's) Multiplex Subcommittee as ``The process of 
combining several messages for transmission over the same signal 
path.''
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    Trailers do not typically have their own electrical power source. 
Thus, an electrical connector is needed to provide electrical current 
between a tractor and a trailer. At present, the most common electrical 
connector used for this purpose in the United States is the SAE J560 
plug/receptacle, which was developed in the 1950s and has been in 
widespread use ever since. This connector has seven pins, providing 
seven electrical paths: Pin one is used as a common ground for the 
other six positive power pins; pin two is used to power clearance and 
side marker lamps; pin three is used to power the left hand turn 
signal; pin four is used to power the stoplamp; pin five is used to 
power the right hand turn signal and hazard signal; pin six is used to 
power the taillamp, marker lamps, and license plate lamps; and pin 
seven is an auxiliary circuit that is not currently used in most 
vehicle combinations. In the past, it has been common practice to power 
trailer ABSs exclusively from pin 4, the stoplamp circuit. This 
involves sharing power with the stoplamp bulbs which are only activated 
when the brakes are applied.
    In a fleet study 8 that NHTSA conducted to support the current 
ABS rulemaking, the agency evaluated other ABS powering approaches, 
including a single 13-pin connector, a separate six-pin connector, and 
another separate connector known as the International 

[[Page 5951]]
Standards Organization (``ISO'') connector. These other powering 
approaches used dedicated electrical circuits, including separate, 
fully dedicated positive and ground wires, to power the trailer ABS.

     8  ``An In-Service Evaluation of the Performance, 
Reliability, Maintainability, and Durability of Antilock Braking 
Systems for Semitrailers,'' U.S. Department of Transportation/ NHTSA 
Report No. DOT HS 808 059, October 1993
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    In the March 1995 final rule, NHTSA decided to require dedicated 
powering for trailer ABSs and to require that towing vehicles have a 
corresponding separate circuit. (60 FR 13248-13250) The agency 
explained that this requirement provides the most dependable source of 
electrical power from the tractor to ensure the functioning of the 
trailer's ABS.
    In petitions for reconsideration of the March 1995 final rule, 
American Automobile Manufacturers Association (AAMA), Midland-Grau, and 
TTMA requested that NHTSA interpret the requirement for dedicated power 
so that the ABS powering circuit need not be exclusively used for ABS. 
AAMA and Midland-Grau requested the agency to allow other uses for this 
circuit, such as powering interior van trailer lights and multiplex 
signaling. ATA reasserted its concern that the requirement for a 
separate circuit would be costly and would create operational problems, 
because it would result in the use of a second tractor/trailer 
electrical connector, which would be used only infrequently, until the 
number of tractors and trailers with ABS increased, to the point where 
a high percentage of vehicles in combination would be ABS equipped. ATA 
stated a strong preference for a requirement that would allow the 
continued use of the SAE J560 connector. In a September 6, 1995 letter, 
ATA requested that the agency interpret the requirement for a separate 
electrical circuit in such a way as to allow the continued use of the 
SAE J560 connector.
    In the December 1995 final rule responding to petitions for 
reconsideration, NHTSA denied the petitioners' request to permit other 
uses for the separate ABS circuit. Based on information available at 
that time, NHTSA concluded that it was necessary for the ABS on towed 
vehicles to receive full-time power through a dedicated circuit to 
reduce the possibility of the ABS being inoperative due to lack of 
power. The agency found no basis in the publicly available data on 
which to alter its view that the dedicated circuit was necessary.
2. Petitions for Reconsideration of December 1995 Final Rule
    In response to the December 1995 final rule, each petitioner 
supported the Industry Consensus Position to permit continuous powering 
to the trailer ABS. TMA stated that new information and industry 
commitments support a decision to delete the dedicated powering 
requirement and replace it with a continuous powering requirement. TMA, 
Midland-Grau, ATA, AlliedSignal, HDBMC, and VES supplied data which 
indicated that adequate levels of electrical power could be supplied to 
trailer ABSs on non-dedicated circuits. Midland-Grau strongly supported 
the continuous powering requirement with the stoplamp circuit as a back 
up, provided that the ABS circuit could be used to power warning and 
other monitoring systems. ATA supported the Industry Consensus 
Position. That organization continues to believe that intermittent 
powering through the stoplamp circuit provides adequate electrical 
energy to power the trailer ABS, citing its analysis of additional data 
and industry commitments to upgrade tractor electrical systems. 
Nevertheless, ATA agreed to a requirement for continuous power instead 
of stoplamp power, if the trailer ABS power supply circuit could be 
used for other purposes.
    All petitioners opposed the requirement for dedicated powering with 
a separate ground. TMA, ATA, Midland-Grau, AlliedSignal, and HDBMC 
stated that the separate ground requirement, which is an integral part 
of dedicated powering, requires the use of diodes in the trailer ABS's 
electrical control unit (ECU) which reduce the voltage available for 
trailer ABS. They further stated that requiring two grounds could 
create ``ground loop circuits,'' which may create unexpected voltage 
differences between various electrical systems on vehicles. This may 
result in electrical shorting and the possibility of electrical fires.
    In support of their petitions, the petitioners provided new 
information relating to the voltage requirements of the new generation 
of ECUs, the amperage requirements of new modulators, and the voltage 
losses associated with dedicated power circuits. The petitions also 
stated that the petitioners are committed to meeting new voluntary 
powering standards and to completing the development of a new 
generation of electronic communications systems.
3. Agency's Decision
    The agency's decisions are based on the new information provided in 
the public record by the petitioners, as described above and discussed 
more fully below. Based on this information, as well as recent studies 
9 by the agency, NHTSA has decided to amend FMVSS No. 121 
consistent with the Industry Consensus Position and to replace the 
requirement for dedicated power to the trailer ABS with a requirement 
for continuous power. Stoplamp power will continue to be required to 
provide back-up power for the trailer ABS. In addition, the agency has 
decided to delete the requirement for a separate ABS ground and to 
allow a common ground for ABS trailer powering. The agency emphasizes 
that continuous power rather than intermittent power through the 
stoplamp circuit is needed as a primary powering source to ensure the 
safe operation and reliability of trailer ABS and to provide the 
capability to signal a continuous warning of a trailer ABS malfunction 
to the cabs of towing units.

    \9\ Winkler, C.B., Bogard, S.E., Bowen, M.A., Ganduri, S.M., and 
Lindquist, D.J. ``An Operational Field Test of Long Combination 
Vehicles Using ABS and C-Dollies'', University of Michigan 
Transportation Research Institute Report No. 95-45-2, under USDOT/
NHTSA Contract No. DTNH22-92-D-07003, November 1995
    Flick, M. A., ``NHTSA's Heavy Duty Vehicles Brake Research 
Program Report Number 10--Evaluation of Trailer Antilock Braking 
Systems Electrical Powering'', USDOT Report No. HS 808 249, March 
1995.
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    With respect to the safe operation of trailer ABS, an agency report 
10 indicated that a problem can occur if power is interrupted to a 
trailer ABS while it is cycling. Specifically, under lightly loaded or 
empty trailer operating conditions on low coefficient of friction 
surfaces, if a brake application that activates the ABS is fully 
released and then fully applied again, the resulting interruption of 
electrical current through the stoplamp circuit can cause the 
reactivated ABS ECU to misinterpret the wheel speed signals it is 
receiving. The ECU could interpret the signals as meaning that the 
vehicle is stopped and thereupon allow the brakes to be fully applied. 
This would result in locked trailer wheels. Notwithstanding the fact 
that this type of brake application might occur infrequently in real-
world operating conditions, this possibility underlines the importance 
of continuous powering as the primary method of powering trailer ABS, 
and indicates that the stoplamp circuit should not be relied on as more 
than a back-up to primary continuous powering. Data submitted by 
Midland-Grau support the agency's position.

    \10\ USDOT Report No. HS 808 249, March 1995.
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    With respect to the reliability of trailer ABS, NHTSA's decisions 
in earlier rulemakings focused on ensuring that the trailer ABS 
received adequate voltage. In the March 1995 final rule, 

[[Page 5952]]
the agency specified a requirement for a dedicated trailer ABS power 
circuit as the best means to ensure adequate voltage levels (i.e., 9-10 
volts) for trailer ABSs. The agency believed that a separate ground 
wire was also needed to ensure sufficient capacity to provide a return 
path for electrical current that would not be subject to excessive 
voltage drops because the ground wire carried too much current. This 
belief rested on data from the agency's fleet studies.
    On the basis of this new information in the petitions for 
reconsideration, NHTSA has determined that a continuous, but non-
dedicated, source of power and a shared ground will provide sufficient 
power to the trailer ABS. The HDBMC petition stated that all current 
versions of trailer ABSs function at levels as low as 8.5 volts, and 
that ABS modulators have now been designed to draw a maximum of 3 amps. 
The agency agrees with the HDBMC petition that the information 
previously available indicating that trailer ABSs require 9-10 volts to 
remain functional, and that ABS modulators draw 2-6 amps of current, 
has been superceded. This information about the lower power needs of 
new ABS systems indicates that a dedicated power source and a separate 
ground wire are not necessary for ABS power.
    The agency agrees with petitioners that the addition of a separate 
ground wire would necessitate adding diodes to the trailer ECU powering 
circuitry to prevent inadvertent ground loops that may result in 
electrical short circuits or electrical fires. These added diodes would 
result in a 0.7 volt decrease to the trailer ECU, an outcome 
inconsistent with ensuring adequate power levels.
    Based on the above considerations, NHTSA has decided to modify 
sections 5.1.6.3 and 5.5.2 to require continuous power to trailer ABSs, 
to permit the circuit to be shared with other devices and to allow 
trailer ABS powering circuits to share a common ground with other 
electrical powering circuits.
    Powering electrical devices other than the trailer ABS from the ABS 
power circuit has the potential to compromise the circuit's ability to 
power the trailer ABS. A recently completed study on long combination-
unit vehicles (LCVs) 11 highlights the need to design all the 
elements of tractor/trailer electrical system to ensure adequate 
electrical power levels. Among other things, that study considered 
whether sufficient voltage could be supplied to the rear trailers and 
dollies of multiple trailer combinations (especially triple trailer 
combinations) on the same circuit. The study found that even with 
special wiring and well maintained connectors, it was necessary for the 
electrical systems of tractors to supply 13.3 volts and for the ABS on 
dollies and trailers to operate on no more than 9.0 volts in order to 
ensure that sufficient electrical power could be supplied. Some of the 
tractors in the test program were not able to consistently provide the 
13.3 volts of electrical power through the stoplamp circuit, and some 
of the ABSs needed more than 9.0 volts. In some cases, trailing unit 
ABSs ceased functioning. Accordingly, a manufacturer can ensure 
adequate powering for trailer ABSs by providing adequately sized 
electrical wiring in both towing and towed units, by providing towing 
units with heavy duty electrical charging systems, and by employing low 
voltage demand lighting systems.

    \11\ University of Michigan Transportation Research Institute 
Report No. 95-45-2, under USDOT/NHTSA Contract No. DTNH22-92-D-
07003, November 1995
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    The agency agrees with Midland-Grau's position that the only other 
devices which should share this circuit are warning, monitoring, or 
other signaling/communications devices. Additional uses that would not 
likely pose problems are low power demand components or devices which 
are powered when the vehicle is stopped or in reverse, conditions in 
which the ABS would not be in use. However, the agency has decided not 
to specify the devices that may share the use of the trailer ABS power 
circuit. The agency is confident heavy vehicle manufacturers and users 
recognize the need for appropriate restrictions and notes that industry 
is working, through various SAE and other technical committees, to 
establish performance standards for electrical systems that power 
tractor and trailer ABS systems. These anticipated industry standards 
are expected to include objective performance test procedures, 
measurement criteria, and, in some cases, target performance levels. 
Several of the petitioners specifically referenced SAE J2272, Truck 
Tractor Power Output for Trailer ABS, and its TMC equivalent, RP137, 
Antilock Electrical Supply for Tractors Through the SAE J560 Connector, 
and indicated that they were committed to designing and using products 
that meet these specifications. TTMA stated that it was developing a 
comparable companion standard for trailer electrical systems.
    NHTSA will monitor these efforts to develop consensus industry 
standards and the commitment made by heavy vehicle manufacturers and 
users to meet these voluntary standards. Efforts to develop consensus 
on this topic have been under way since 1988, when WABCO submitted a 
petition on trailer ABS powering schemes (53 FR 39751, October 12, 
1988). The agency anticipates that this powering issue can be resolved 
without further delays in the implementation schedule for the trailer 
powering and in-cab indicator requirements.
    After evaluating these voluntary standards, NHTSA may consider 
further rulemaking to amend FMVSS No. 121 to require minimum voltage 
levels at the tractor or to limit the use of the ABS power circuit if 
such requirements appear necessary to ensure the adequacy of power to 
the trailer ABS. Such a rulemaking action would be consistent with the 
President's Regulatory Reinvention Initiative which encourages 
regulatory agencies, when appropriate, to adopt voluntary standards 
established and followed by the private sector.

B. Trailer Malfunction Indicators

    FMVSS No. 101, Controls and Displays, sets forth requirements for 
the location, identification, and illumination of motor vehicle 
controls and displays. Table 2(a) of the standard lists various 
telltales that are required in a motor vehicle to advise the driver of 
the status of a variety of vehicle systems. For air brake equipped 
trucks, these include telltales for brake system air pressure and for 
ABS malfunction in the truck.
    In the March 1995 final rule, NHTSA required lamps in the cab of 
truck tractors to indicate any malfunction with the ABS of any towed 
vehicles. (60 FR 13244, 13245) The agency also required trailers to 
supply trailer ABS malfunction signals to the tractor. The agency 
explained that it is essential that a driver be notified about an ABS 
malfunction in the trailer, so that the problem can be corrected. The 
agency cited results from the ABS fleet study which indicated that 
drivers are more likely to observe a tractor in-cab indication of a 
trailer ABS malfunction than they are a trailer-mounted lamp. The study 
also noted that some trailer ABS malfunctions were present for a long 
time, and not reported, because the drivers did not notice that the 
trailer-mounted malfunction lamps were activated. Based on these 
findings, the agency decided that it was necessary to require an in-cab 
trailer ABS malfunction warning light to adequately ensure that such 
malfunctions would be detected and corrected.
    In response to the March 1995 final rule, ATA petitioned the agency 
to delete the requirement for in-cab indication of trailer ABS 
malfunctions. 

[[Page 5953]]
It argued that such a requirement was unnecessary and would needlessly 
complicate the electrical system of the tractor and the electrical 
connector arrangement between tractors and trailers.
    In the December 1995 final rule, NHTSA denied ATA's request to 
delete the in-cab malfunction lamp for the trailer ABS. In explaining 
that the in-cab trailer malfunction lamp is necessary, the agency 
referenced a study that showed that an in-cab malfunction lamp is a 
more effective means of making the driver aware of an ABS malfunction, 
compared with an external malfunction lamp on the trailer.12 NHTSA 
also disagreed with ATA's statement that the requirement for two 
malfunction indicators unreasonably complicates the electrical systems 
in combination vehicles, based on comments by brake and vehicle 
manufacturers stating that it was appropriate to have an indicator in 
the towing unit cab.

    \12\ ``An In-Service Evaluation of the Performance, Reliability, 
Maintainability, and Durability of Antilock Braking Systems for 
Semitrailers,'' U.S. Department of Transportation/NHTSA Report No. 
DOT HS 808 059, October 1993.
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    In response to the December 1995 final rule, the Industry Consensus 
Position stated that ultimately it is essential to provide drivers an 
in-cab indication of a trailer(s) ABS malfunction, but that requiring 
the in-cab indicator by 1997 would likely impede the implementation of 
a new high speed data transmission protocol SAE J1939 that is now being 
developed by the SAE. This new protocol is expected to become the 
recognized method for providing signaling capability between tractors 
and trailers for a wide variety and number of devices and systems, 
including trailer ABS malfunction indications. The Industry Consensus 
Position is that delaying the implementation date of the in-cab 
malfunction warning requirement for trailer ABS malfunctions to March 
1, 2001, would provide sufficient time to fully develop the SAE J1939 
protocol and would thus preclude the need for a two-step implementation 
process.
    Based on information provided in the petitions, NHTSA has decided 
to grant the requested delay for the trailer in-cab malfunction 
indicator. By delaying the requirement, the agency will enable the 
manufacturers to move directly and promptly to in-cab failure 
indicators that will use the new SAE protocol, thereby saving the cost 
of installing indicators based on current technology. The delay will 
also avoid the compatibility problems between new and old tractors and 
trailers in the field and the associated costs and potential 
maintenance problems associated with such a transition. The petitions 
indicate a strong commitment to develop an SAE J1939-based final 
solution. The agency anticipates that heavy vehicle manufacturers and 
users will be able to develop and implement SAE J1939 and that further 
delays in the implementation of this requirement will neither be 
requested nor necessary.
    NHTSA further notes that the external trailer indicator will still 
advise a driver about a trailer ABS malfunction during this interim 
period, when an in-cab indicator is not required. Notwithstanding the 
need to rely on the external trailer indicator during this interim 
period, NHTSA continues to view the in-cab trailer ABS malfunction 
indicator as the best method for informing a driver of a trailer ABS 
malfunction, based on the data and other information referenced in the 
final rule.

C. External Trailer Malfunction Indicator

    In previous notices, NHTSA emphasized the interrelationship between 
the in-cab trailer malfunction indicator and the external trailer 
malfunction indicator. In the September 28, 1993, notice of proposed 
rulemaking (60 FR 13221, September 28, 1993) which led to the March 
1995 final rule, the agency stated that the eight-year period for the 
interim external trailer requirement was intended to represent the 
average lifespan of a truck tractor and that

    The external lamp would not be necessary on new trailers 
manufactured after the end of that period because by that time, a 
significant majority of tractors in the heavy vehicle fleet, which 
would be responsible for the vast majority of miles driven by 
tractors, would be manufactured in compliance with the requirement 
for an in-cab lamp capable of receiving a malfunction signal from a 
trailer.

    In the final rule, the agency reiterated this view, although it 
talked in terms of ``ABS and non-ABS equipped tractors'' as a shorthand 
for tractors equipped with ABS malfunction indicators.
    NHTSA's decision to delay the in-cab malfunction indicator for 
trailer ABS from March 1, 1997 until March 1, 2001, will delay the 
entry of tractors equipped with such indicators into the fleet. To 
provide drivers of tractors without in-cab indicators with a warning of 
trailer ABS failure, the agency has decided to extend the transition 
period during which a trailer must be equipped with an external 
malfunction indicator. The external indicators will be required from 
March 1, 1998 until March 1, 2009, three years later than the date 
established in the December 1995 final rule. Accordingly, a trailer 
must still be equipped with an external ABS indicator during the time 
period in which there is no in-cab trailer ABS malfunction indicator 
requirement in effect as well as for an additional eight years after 
the in-cab trailer malfunction indicator requirement takes effect. As 
explained in previous notices, the additional eight-year transition 
period represents the typical life cycle of tractors. Based on these 
considerations, NHTSA has decided to amend S5.2.3.3 to require each 
trailer (including a trailer converter dolly) manufactured on or after 
March 1, 1998 and before March 1, 2009 to be equipped with an external 
ABS malfunction indicator lamp.

IV. Rulemaking Analyses and Notices

A. Executive Order 12866 and DOT Regulatory Policies and Procedures

    This notice has not been reviewed under Executive Order 12866. 
NHTSA has considered the impacts of this rulemaking action and 
determined that it is not ``significant'' within the meaning of the 
Department of Transportation's regulatory policies and procedures. In 
connection with the March 1995 final rules, the agency prepared a Final 
Economic Assessment (FEA) describing the economic and other effects of 
this rulemaking action. Summary discussions of those effects were 
provided in the ABS final rule. For persons wishing to examine the full 
analysis, a copy is in the docket.
    The amendments in this final rule do not make those effects any 
more stringent, and in some respects make it easier for a manufacturer 
to comply with them. Specifically, by eliminating the requirement for 
the dedicated ABS circuit and delaying the trailer in-cab malfunction 
indicator by four years, tractor and trailer manufacturers will be able 
to develop new methods of communicating trailer ABS information to the 
tractor. Thus, for these four years, tractor manufacturers will not 
have to provide a trailer in-cab malfunction indicator. After this four 
year period, truck and trailer manufacturers will incur some additional 
cost associated with ABS communications. This cost will depend on the 
communication technique employed, i.e., multiplexing, Radio Frequency 
(RF) signaling, or a separate circuit.

B. Regulatory Flexibility Act

    NHTSA has also considered the effects of both this final rule or 
the original final rule under the Regulatory Flexibility Act. I hereby 
certify that it will not have a significant economic impact on a 
substantial number of small 

[[Page 5954]]
entities. Accordingly, the agency has not prepared a final regulatory 
flexibility analysis.
    NHTSA concluded that the March 1995 final rule had no significant 
impact on a substantial number of small entities. Thus, the revised 
final rule, which temporarily reduces costs associated with the March 
1995 final rule, will not have a significant economic impact on a 
substantial number of small entities.

C. National Environmental Policy Act

    NHTSA has analyzed this rulemaking action for the purposes of the 
National Environmental Policy Act. The agency has determined that 
implementation of this action will not have any significant impact on 
the quality of the human environment.

D. Executive Order 12612 (Federalism)

    NHTSA has analyzed this action under the principles and criteria in 
Executive Order 12612. The agency has determined that this notice does 
not have sufficient Federalism implications to warrant the preparation 
of a Federalism Assessment. No State laws will be affected.

E. Civil Justice Reform

    This final rule does not have any retroactive effect. Under 49 
U.S.C. 30103, whenever a Federal motor vehicle safety standard is in 
effect, a State may not adopt or maintain a safety standard applicable 
to the same aspect of performance which is not identical to the Federal 
standard, except to the extent that the State requirement imposes a 
higher level of performance and applies only to vehicles procured for 
the State's use. 49 U.S.C. 30161 sets forth a procedure for judicial 
review of final rules establishing, amending or revoking Federal motor 
vehicle safety standards. That section does not require submission of a 
petition for reconsideration or other administrative proceedings before 
parties may file suit in court.

List of Subjects in 49 CFR Part 571

    Imports, Motor vehicle safety, Motor vehicles, Rubber and rubber 
products, Tires.

    In consideration of the foregoing, the agency is amending Standard 
No. 121, Air Brake Systems, in title 49 of the Code of Federal 
Regulations at part 571 as follows:

PART 571--[AMENDED]

    1. The authority citation for part 571 continues to read as 
follows:

    Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166, 
delegation of authority at 49 CFR 1.50.

    2. Section 571.121 is amended by revising S5.1.6.2(b), S5.1.6.3, 
S5.2.3.2, S5.2.3.3 and S5.5.2 to read as follows:


Sec. 571.121  Standard No. 121; Air brake systems.

* * * * *
    S5.1.6.2  Antilock malfunction signal.
    * * *
    (b) Each truck tractor manufactured on or after March 1, 2001, and 
each single unit vehicle manufactured on or after March 1, 2001, that 
is equipped to tow another air-braked vehicle, shall be equipped with 
an electrical circuit that is capable of transmitting a malfunction 
signal from the antilock brake system(s) on one or more towed 
vehicle(s) (e.g., trailer(s) and dolly(ies)) to the trailer ABS 
malfunction lamp in the cab of the towing vehicle, and shall have the 
means for connection of this electrical circuit to the towed vehicle. 
Each such truck tractor and single unit vehicle shall also be equipped 
with an indicator lamp, separate from the lamp required in S5.1.6.2(a), 
mounted in front of and in clear view of the driver, which is activated 
whenever the malfunction signal circuit described above receives a 
signal indicating an ABS malfunction on one or more towed vehicle(s). 
The indicator lamp shall remain activated as long as an ABS malfunction 
signal from one or more towed vehicle(s) is present, whenever the 
ignition (start) switch is in the ``on'' (run) position, whether or not 
the engine is running. The indicator lamp shall also be activated as a 
check of lamp function whenever the ignition is turned to the ``on'' or 
``run'' position. The indicator lamp shall be deactivated at the end of 
the check of lamp function unless a trailer ABS malfunction signal is 
present.
* * * * *
    S5.1.6.3  Antilock power circuit for towed vehicles. Each truck 
tractor manufactured on or after March 1, 1997, and each single unit 
vehicle manufactured on or after March 1, 1998, that is equipped to tow 
another air-braked vehicle shall be equipped with one or more 
electrical circuits that provide continuous power to the antilock 
system on the towed vehicle or vehicles whenever the ignition (start) 
switch is in the ``on'' (run) position. Such a circuit shall be 
adequate to enable the antilock system on each towed vehicle to be 
fully operable.
* * * * *
    S5.2.3.2 Antilock malfunction signal. Each trailer (including a 
trailer converter dolly) manufactured on or after March 1, 2001, that 
is equipped with an antilock brake system shall be equipped with an 
electrical circuit that is capable of signaling a malfunction in the 
trailer's antilock brake system, and shall have the means for 
connection of this antilock brake system malfunction signal circuit to 
the towing vehicle. The electrical circuit need not be separate or 
dedicated exclusively to this malfunction signaling function. The 
signal shall be present whenever there is a malfunction that affects 
the generation or transmission of response or control signals in the 
trailer's antilock brake system. The signal shall remain present as 
long as the malfunction exists, whenever power is supplied to the 
antilock brake system. Each message about the existence of such a 
malfunction shall be stored in the antilock brake system whenever power 
is no longer supplied to the system, and the malfunction signal shall 
be automatically reactivated whenever power is again supplied to the 
trailer's antilock brake system. In addition, each trailer manufactured 
on or after March 1, 2001, that is designed to tow another air-brake 
equipped trailer shall be capable of transmitting a malfunction signal 
from the antilock brake system(s) of additional trailers it tows to the 
vehicle towing it.
* * * * *
    S5.2.3.3 Antilock malfunction indicator. In addition to the 
requirements of S5.2.3.2, each trailer (including a trailer converter 
dolly) manufactured on or after March 1, 1998, and before March 1, 
2009, shall be equipped with an external indicator lamp that is 
activated whenever there is a malfunction that affects the generation 
or transmission of response or control signals in the trailer's 
antilock brake system. The indicator lamp shall remain activated as 
long as such a malfunction exists, whenever power is supplied to the 
antilock brake system. Each message about the existence of such a 
malfunction shall be stored in the antilock brake system whenever power 
is no longer supplied to the system, and the malfunction signal shall 
be automatically reactivated when power is again supplied to the 
trailer's antilock brake system. The indicator lamp shall also be 
activated as a check of lamp function whenever power is supplied to the 
antilock brake system and the vehicle is stationary. The indicator lamp 
shall be deactivated at the end of the check of lamp function unless 
there is a malfunction or a message about a malfunction that existed 
when power 

[[Page 5955]]
was last supplied to the antilock brake system.
* * * * *
    S5.5.2 Antilock system power--trailers. On a trailer (including a 
trailer converter dolly) manufactured on or after March 1, 1998 that is 
equipped with an antilock system that requires electrical power for 
operation, the power shall be obtained from the towing vehicle through 
one or more electrical circuits which provide continuous power whenever 
the powered vehicle's ignition (start) switch is in the ``on'' (run) 
position. The antilock system shall automatically receive power from 
the stoplamp circuit, if the primary circuit or circuits are not 
functioning. Each trailer (including a trailer converter dolly) 
manufactured on or after March 1, 1998 that is equipped to tow another 
air-braked vehicle shall be equipped with one or more circuits which 
provide continuous power to the antilock system on the vehicle(s) it 
tows. Such circuits shall be adequate to enable the antilock system on 
each towed vehicle to be fully operable.
* * * * *
    Issued on: February 12, 1996.
Ricardo Martinez,
Administrator.
[FR Doc. 96-3382 Filed 2-13-96; 8:45 am]
BILLING CODE 4910-59-P