Bendix Commercial Vehicle Systems EC-15 ANTILOCK CONTROLLER ASSY 4/08 - Manual (Page 6)

6
FIGURE 5 - M-21 ™ MODULATOR
SOLENOID
CONNECTOR
EXHAUST
SUPPLY
MOUNTING
HOLES
DELIVERY
SUPPLY
ANTILOCK SYSTEM OPERATION -
COMPONENT FAILURE
The Bendix ® EC-15 ™ controller handles equipment failure
using a conservative fail-safe philosophy. Any single electrical
failure of a component devoted to antilock braking, results
in simultaneous illumination of the antilock condition lamp
on the dash, a disabling of all or part of the antilock system,
and reversion to standard braking on wheels no longer under
the control of antilock. When coping with wheel equipment
(modulator or wheel speed sensor/exciter) failure, the EC-15
™
controller divides and separates the brakes diagonally. For
example; if the modulator at the right front wheel has a broken
wire lead, the EC-15
™ controller disables the antilock function
for BOTH the right front and left rear wheels. The antilock
will continue to function on the left front and right rear wheels
and will remain under the control of the EC-15
™ controller.
(Note: Right and left, front and rear are determined from the
driver’s seat. Left front is therefore the corner closest to the
driver). Depending upon the type of failure and its position of
occurrence the EC-15
™ controller either disables all, or only
a portion, of the antilock system. A power or controller failure,
for instance, will result in complete disabling of the antilock
system and reversion to standard braking on all wheels.
Two or more failures, regardless of their position of
occurrence, will also result in the disabling of the entire
system. With the failed component approach described, the
vehicle will retain improved braking stability after a single
failure. It should be remembered that the driver will be
advised of the degraded antilock operation via the dash
lamp and that standard air braking will still be available on
those brakes where the antilock has been disabled by the
EC-15
™ controller.
ANTILOCK WIRING
The wires that carry information and power into and out of
the EC-15
™ controller are generally grouped and terminate
at a connector. The wire groups or wire harnesses along
with the connectors are most often specified and or supplied
by the vehicle manufacturer. Two examples of the connectors
used on the EC-15
™ controller are illustrated in figures 7 &
8. The wiring harnesses and connectors are weather proof
and the wires that enter the connector are sealed to the
connector. The wire gauge used in the wire harnesses is
specific to the task performed.
When diagnosing wiring in the antilock system the following
general rules apply and should be followed where applicable:
1. It is generally advisable to replace a wire harness rather
than repair individual wires in the harness. If a splice
repair must be made, it is important that the splice be
properly soldered with a rosin flux (not acid based flux)
and made water proof.