Section 1
Introduction
Page 2
Easy-Stop™ Trailer ABS Parts
Parts book PB-96133 lists WABCO Easy-Stop™
replacement parts. To obtain a copy, contact
WABCO North America Customer Care at
855-228-3203.
What Is WABCO’s Easy-Stop™
Trailer ABS?
WABCO’s Easy-Stop™ Trailer ABS is an electronic,
self-monitoring system that works
with standard air brakes. The major components
of the system are the Electronic Control Unit
(ECU)/Valve Assembly, ABS relay (modulator)
valve, tooth wheel and wheel speed sensor.
Refer to Figure 1.2 .
ECU Part Numbers 472 500 001 0, 472 500 012 0
and 472 500 013 0 have an external diagnostics
connector for use with a special diagnostic tool.
These models are also compatible with an MPSI
Pro-Link
®
9000 diagnostic tool and WABCO
cartridge. ECU/Valve Assembly 472 500 011 0 does
not have a diagnostic connector port. Diagnostic
procedures for all of these ECUs are detailed in
Section 5, "Diagnostics" of this manual.
The ABS configuration defines the number of
wheel speed sensors and ABS relay valves used in
a system. For example, a 2S/1M configuration
includes two wheel sensors and one ABS relay
valve. A 2S/2M configuration includes two wheel
sensors and two relay valves. A 4S/2M
configuration includes four wheel sensors and
two ABS relay valves.
How Trailer ABS Works
WABCO ABS is an electronic system that monitors
and controls wheel speed during braking. The
system works with standard air
brake systems.
ABS monitors wheel speeds at all times and
controls braking during wheel lock situations. The
system improves vehicle stability and control by
reducing wheel lock during braking.
The ECU receives and processes signals from the
wheel speed sensors. When the ECU detects a
wheel lockup, the unit activates the appropriate
modulator valve, and air pressure is controlled.
In the event of a malfunction in the system, the
ABS in the affected wheel(s) is disabled; that wheel
still has normal brakes. The other wheels keep the
ABS function.
An ABS warning lamp lets drivers know the status
of the system.
Figure 1.2
1 ECU/Valve Assembly
2 External ABS Relay Valve (not used in
1M configurations)
3 Tooth Wheel
4 Wheel Speed Sensor
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