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OPERATING INSTRUCTIONS
Anti-Lock Brake System (ABS)
Vehicle standards FMVSS No. 121, anti-lock brake
system requires all trailers manufactured after March 1,
1998 with air brake systems to have ABS. Each trailer
(including a trailer converter dolly) shall be equipped with
an anti-lock brake system that controls the wheels of at
least one axle of the trailer. Wheels on other axles of the
trailer may be indirectly controlled by the anti-lock brake
system.
NHTSA Docket 92-29; notice 11 published September
23, 1996 specifies the ABS warning light be mounted
near the rear of the left side of the trailer (See
Figure 3-10.)
Decal or lens marking with ABS to identify the lamp.
The lamp must illuminate one time whenever power is
supplied to the ABS. At any time the light remains on
when power is supplied there is a malfunction to the
system.
The ABS used on the semitrailer is a commercial unit.
Single axle trailers use a two sensor, one modulator
system. Tandem axle semitrailers use a four sensor, two
modulator system. Sensors are located at each hub of
the front and rear axles, and each modulator controls one
side of the trailer.
The ABS is constant powered by the auxiliary (blue)
circuit, center pin on the semitrailer seven way electrical
connector. This circuit must be hot whenever the tractor
keyswitch is on. This circuit must also not be used to
power any additional electrical devices while the
semitrailer is moving forward. However, additional
devices such as remote controls may be powered from
the auxiliary circuit while the semitrailer is stationary.
Back up power to the ABS is supplied through the stop
lamp (red) circuit, No. 4 pin on the seven way connector,
and ground is supplied by the white wire, No. 1 pin.
3-26
The auxiliary (blue) circuit is for powering the
semitrailer ABS. This circuit must be hot when
the tractor key switch is on. No other electrical
devices may be powered by this circuit while the
semitrailer is moving forward.
Malfunction in the ABS is signaled by illumination of the
ABS warning lamp located at the left rear side of the
semitrailer. The warning lamp will come on and stay on
while power is supplied to the ABS on a moving vehicle, if
there is a fault. If a fault in the ABS exists, normal braking
will still occur, but wheels may lock. The semitrailer is still
operable, but the system should be serviced as soon as
possible.
If a fault exists in the semitrailer ABS, normal
braking will occur, but wheels may lock. Service
the ABS as soon as possible.
Refer to ABS maintenance manual supplied with
semitrailer to answer basic questions for the anti-lock
brake system, obtain outline procedures on how to
adjust, test, remove, and install ABS components, as well
as how to test for faults in the system by using "Blink
Code Diagnostics"; and illustrates ABS components,
wiring, and plumbing installation diagrams.
CAUTION
CAUTION
F-618-0911 Edition
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