Technical information

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Technician Guidelines for Antilock Braking Systems
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J1708 An SAE Recommended Practice for serial exchange of vehicle-
based, noncritical parametric information. This standard estab-
lishes the hardware and protocol requirements for the serial
data bus. See J1587.
Jackknife A condition that can occur when either tractor, trailer, or tractor
and trailer wheels lose traction and lateral vehicle stability
cannot be maintained.
Lateral Stability The resistance of a vehicle to forces which attempt to change its
direction of travel. Maximum lateral stability is achieved at zero
percent wheel slip (free rolling travel).
LED Light-emitting diode used in some ABS diagnostic systems to
convey diagnostic information.
Malfunction Indicator Lamp A lamp that becomes active whenever an ABS is not fully
functional. The tractor/truck lamp is on the instrument panel. A
trailer/dolly in-cab indicator is not required by law until March
2001. However, an external trailer/dolly indicator lamp is
required, effective March 1998. By March 2009, the external
lamp will no longer be required. Also called Warning Lamp or
Failure Lamp.
Manifold The central device on which the modulators of a two- or three-
channel system may be commonly mounted.
Microcontroller An application-specific microprocessor geared around a specific
control function. Also referred to as “computer chips.”
Modulator See ABS Modulator Valve.
Mu Refers to the Greek letter µ which represents coefficient of
friction. See Coefficient of Friction.
NHTSA National Highway Traffic Safety Administration. This division of
the U.S. Department of Transportation regulates the safety of
new vehicles. NHTSA is the federal agency that requires the
installation of ABSs on new commercial vehicles.
Non-Volatile Memory (NOVRAM) Solid-state electronics capable of retaining electrical information
in the absence of system power. This is how diagnostics infor-
mation is saved in the ABS ECU.