Technical information

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Technician Guidelines for Antilock Braking Systems

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Current Current represents the flow of electrons through a conducting

medium, such as copper. Current is measured in amperes or

amps and can be derived through the following formula:

Amp = Volt/Ohm or I=V/R.

Cycle A single sequence of pressure application and release during

ABS operation. This cycle repeats during an ABS event as long

as impending wheel lock-up is identified. Also referred to as

“cycling.”

Data Link The TMC/SAE J1708/J1587 Serial Data Link Standard used in

most vehicle-mounted ECUs.

Diagnostics A method of identifying faulty components or parameters. For

example, a series of LED lights may be used to identify specific

ABS components that need to be serviced or corrected.

Diagonal Split The case in which ABS is disabled on both the specific wheel

with an ABS failure and its diagonal counterpart to maintain

vehicle control during emergency stops.

Dynamic Fault A fault detected with the wheel speed sensors or modulators

when the wheels are rotating. See Static Fault.

Electronic Control Unit (ECU) An on-board vehicle computer that controls the ABS, traction

control and diagnostic functions. The ECU receives input sig-

nals, processes the information, and sends output signals to the

necessary ABS components.

Electromagnetic Interference Electromagnetic interference (EMI) disrupts the proper opera-

tion of an electronic device or system. EMI is caused by electro-

magnetic field(s).

EPROM EPROM stands for Erasable Programmable Read Only Memory.

The term refers to an integrated circuit that contains the ABS

control algorithm.

Exciter A metal ring, normally with 100 evenly spaced teeth, although

sometimes with 80 or 120 teeth, depending on tire size. It is

usually attached to the barrel of the hub on each ABS-moni-

tored wheel. When the wheel rotates, the teeth move past the

wheel speed sensor pickup to create an electrical signal that the

ECU uses to determine wheel speed. Also called a Tooth Wheel.