Bendix EC-14 ANTILOCK CONTROLLER User Manual
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Bendix® EC-14™ AntiLock Controller Assembly
MOUNTING HOLES (4)
SD-13-4784
30 PIN WIRE
HARNESS CONNECTOR
DIAGNOSTICS
WINDOW
DESCRIPTION
GENERAL
Bendix trailer antilock systems utilizing the EC-14
electronic controller assembly provide axle braking control
for buses, trucks, and truck trailers. By controlling "wheel
lock-up" during aggressive braking, the trailer retains a high
degree of stability and steerability while braking, and vehicle
stopping distance may be reduced.
In order to provide axle control antilock, the EC-14™ controller
is used in combination with the following components:
• Four individual wheel speed sensors.
• One combination modulator-relay valve.
• One stand alone modulator valve.
• Antilock condition lamp (dash mounted).
PHYSICAL
The EC-14™ controller electronics, which regulate the function
of the antilock system, are contained in a die cast aluminum
housing and are environmentally protected by silicone
FIGURE 1 - EC-14™ ANTILOCK CONTROLLER ASSEMBLY
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encapsulation. The metal housing, coupled with the design
of the digital electronics, is intended to provide a high degree
of protection from radio and electromagnetic interference.
A diagnostics display window with 9 light emitting diodes
(LEDs) and a magnetically actuated Reset switch is
incorporated in the housing for troubleshooting and
diagnostic purposes.
Two electrical connectors are currently used on the EC-14
controller, one for connection to the antilock system
components (30 pin, Packard Electric, 150 series "Metripack”) and one for connection to a combination
modulator-relay valve (4 pin, Molex).
MOUNTING
The EC-14™ controller is specifically designed to be mounted
to a modulator-relay valve assembly , such as the Bendix
M-12™ modulator (reference SD-13-4772). When the
EC-14™ controller is mounted on a modulator assembly the
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FIGURE 2 - MC-14™ ANTILOCK BRAKE SYSTEM
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DIAGNOSTIC
WINDOW
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M-12
MODULATOR
ASSEMBLY
EC-14
MODULATOR
EXHAUST
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CONTROLLER
WIRE HARNESS
CONNECTOR
SERVICE
PORT
SOLENOID
EXHAUST
SUPPLY (2)
DELIVERY PORTS (4)
FIGURE 3 - MC-14™ MODULATOR CONTROLLER ASSEMBLY
resulting assembly receives a different designation. For
example, when the EC-14™ antilock controller is mounted
on the M-12™ modulator the resulting assembly is known
as a MC-14™ modulator controller (see Figure 3).
EC-14™ CONTROLLER INFORMATION
INPUTS AND COMMAND OUTPUTS
GENERAL
The EC-14™ controller receives information from several
components in the antilock system and, based on these
inputs, issues commands or delivers information. Some
portions of the EC-14™ controller both receive and deliver
commands and information.
INPUTS
Wheel Speed Information is provided to the EC-14
controller via a wiring harness from individual speed sensors
located in the trailer wheels or axle housing. Working in
conjunction with an exciter or tone ring, the speed sensors
provide information to the EC-14™ controller in the form of an
AC signal which varies in voltage and frequency as the speed
of the wheel increases or decreases.
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The EC-14™ controller is designed to receive wheel speed
information, from various wheel speed sensor models, at
the rate of 100 pulses per wheel revolution. The EC-14
controller is able to simultaneously receive, and individually
interpret, speed signals from four wheel speed sensors (2
axles).
Vehicle Power is supplied to the EC-14™ controller from
the from the ignition switch through a fuse or circuit breaker.
The electrical ground for the EC-14™ controller is the vehicle
chassis.
A Stop Light Switch connection to the EC-14™ controller
is provided and serves to “signal” the EC-14™ controller of all
brake applications. Although the stop light switch connection
enhances the EC-14™ antilock controller performance, a loss
of the stop light switch “signal” will not prevent antilock
operation.
OUTPUTS
Modulators, like the Bendix® M-12™ and M-21™ or M-22™,
are the means by which the EC-14™ antilock controller is
able to modify driver applied air pressure to the service
brakes. The EC-14™ controller is able to simultaneously
and independently control two modulator assemblies.
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DEUTSCH 2 PIN
CONNECTOR
PACKARD 2 PIN
CONNECTOR
STRAIGHT WS-20
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WHEEL SPEED SENSOR
FIGURE 4 - WS-20™ WHEEL SPEED SENSORS & CONNECTORS
SPEED SENSOR
MOUNTING
BLOCK
100 TOOTH SPEED
SENSOR EXCITER
RING
WS-20™ WHEEL
SPEED SENSOR
(90 DEG.)
90° WS-20™ WHEEL
SPEED SENSOR
BRAKE DRUM
FIGURE 4A - WS-20
4
HUB ASSEMBLY
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WHEEL SPEED SENSOR INSTALLATION
SUPPLY
PORT
3 PIN WIRE
HARNESS
CONNECTOR
MOUNTING
3 PIN WIRE
HARNESS
CONNECTOR
SUPPLY
PORT
DELIVERY
PORT
HOLE
EXHAUST
M-22™ MODULATOR M-21™ MODULATOR
FIGURE 5 - M-21™ & M-22™ MODULATORS
The EC-14™ controller is designed to be mounted directly
on a modulator relay valve assembly like the M-12
modulator. The two separate components (EC-14™ controller
and M-12™ modulator) become a single assembly. The
M-12™ modulator is a combination valve consisting of a
standard relay valve and solenoid assembly. The M-12
modulator replaces the standard relay valve used to speed
up the application and release of the vehicle’s rear axle
brakes. An internal, four pin, wiring harness connects the
EC-14™ controller to the M-12™ modulator solenoid assembly .
For additional information and service procedures see Bendix
Service Data Sheet SD-13-4772.
In addition to the M-12™ modulator, the EC-14™ controller
also controls a single, external modulator like the M-21™ or
M-22™. Connected to the EC-14™ controller via a wire
harness, the M-21™ or M-22™ modulator is essentially a
high capacity, on/off air valve that incorporates a pair of
electrical solenoids for control. The solenoids provide the
electric-air link between the antilock controller electronics
and the air brake system. Unlike the M-12™, the M-21™ or
M-22™ modulator is not combined with a service relay valve.
For additional information and service procedures see Bendix
Service Data Sheet SD-13-4793.
A Dash Light and its electrical relay is connected to, and
controlled by , the EC-14™ controller and serves as a means
of advising the driver of the condition of the antilock system.
MOUNTING
EXHAUST
HOLE
A connection to the Engine or T ransmission Ret arder is
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provided on the EC-14™ controller which allows the EC-14
controller to temporarily “disable” the retarder during certain
modes of operation. While the EC-14™ controller is capable
of this function, and connections are provided, it is not always
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used. Use of the retarder disable function is not essential
but highly recommended for vehicles equipped with a retarder .
The Data Link function enables the EC-14™ controller to
“report” its operating condition to a specialized, external
computer in response to certain commands it receives. The
EC-14™ controller data link configuration conforms to S.A.E.
standard J1708 and the protocol, or coded language used,
conforms to S.A.E. standard J1537. There are two
connections to the EC-14™ controller devoted to the data
link. While the EC-14™ controller is capable of this function,
and connections are provided, it is not always used. Use of
the data link is not essential for the EC-14™ controller to be
functional.
OPERATION
OPERATIONAL PHILOSOPHY
The Bendix® EC-14™ controller provides axle braking control
by using four speed sensors and two modulators. By
monitoring the rate of deceleration during braking, and
subsequently adjusting the brake application pressure to
each axle, the EC-14™ controller is able to provide improved
braking while maintaining vehicle stability .
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Rear Axle Brakes - The vehicle’s rear axle brakes are
controlled by the MC-14™ modulator controller (EC-14
controller and M-12™ modulator). Like the standard service
relay valve it replaces, the M-12
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modulator delivers brake
application pressure to the service chambers on the rear
axle equally. Two speed sensors on the rear axle “report”
changes in acceleration and deceleration to the EC-14
controller. If required, the EC-14™ controller adjusts the
application pressure to the rear axle service brakes, via the
M-12™ modulator, based on the wheel behavior “reported”
to it by the speed sensors. In the case of vehicles equipped
with tandem rear axles (6x2, 6x4), the speed sensors are
installed on the axle that is most likely to lose traction first.
The MC-14™ modulator controller controls all service brakes
on the tandem equally .
The EC-14™ controller utilizes a “Select Smart” brake control
philosophy for the rear axle brakes. This means that the
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EC-14
controller will initially adjust application pressure to
all rear axle service chambers based on the speed information
from the first wheel to approach a locked condition. The
initial pressure adjustment will attempt to prevent all wheels
on the axle(s) from locking. If a substantial braking difference
is detected between the two wheels on the axle equipped
with the speed sensors, the EC-14
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controller will override
the first air pressure adjustment and allow one wheel to
lock. Both wheels including the locked wheel will continue
to be monitored for speed and braking difference changes
that would require pressure adjustments.
Steering Axle Brakes - The steering axle brakes are
controlled by the EC-14™ controller and the M-21™ or M-22
modulator. Although connected to the EC-14™ controller via
a wire harness, the M-21™ or M-22™ modulator is not an
integral part of the MC-14™ modulator controller assembly .
Brake application air passes through the M-21™ or M-22
modulator on its way to the front axle service chambers
from the foot valve.
Two speed sensors on the front axle “report” changes in
acceleration and deceleration to the EC-14™ controller.
The EC-14™ controller uses a “Select Low” brake control
philosophy for the front axle brakes. It will attempt to prevent
wheel lock by adjusting application pressure to both front
axle service chambers based on the speed information from
the first wheel to approach a locked condition. The M-21™ or
M-22™ modulator provides the EC-14™ controller with the
means of adjusting front axle service application pressure
when required.
the same as standard service relay valve and applies air to
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the rear axle service brakes. Because the M-21™ or M-22
modulator does not have a relay valve function, service air
passes through it to a quick release valve and from there to
the front axle service chambers. The service brakes are thus
applied.
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If the speed sensors do not detect an impending wheel lock
up, the EC-14™ controller does not initiate any corrective
action and the vehicle comes to a stop in a normal fashion.
ANTILOCK CONTROLLED BRAKE
APPLICATION - SYSTEM FULLY OPERATIONAL
If a service brake application is made and the speed sensors
detect an impending wheel lockup on an axle, the EC-14
controller will immediately begin modification of the brake
application using the antilock modulator(s) at the affected
axle(s).
Solenoid valves contained in the modulator are energized
and de energized by the EC-14™ controller in order to modify
the brake application. When a solenoid coil is energized its
shuttle moves, and depending upon the function of the specific
solenoid, it either opens or closes, thereby causing the
exhaust or re-application of air pressure to the brake chamber.
The solenoids in either the M-12™ or M-21™ modulator are
controlled independently by the EC-14™ controller. By
opening and closing the solenoid valves in the appropriate
modulator, the EC-14™ controller is actually simulating what
the driver does when he “pumps the brakes”.
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It must be remembered however that unlike the driver, the
EC-14™ controller is able to “pump” brakes on either the
front or rear axle(s), or both, independently and with far greater
speed and accuracy .
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ANTILOCK SYSTEM OPERATION COMPONENT FAULT STRATEGY
The Bendix® EC-14™ controller handles equipment faults
using a conservative fail-safe philosophy . Any single electrical
problem with a component devoted to antilock braking,
results in simultaneous illumination of the antilock condition
lamp on the dash and a troubleshooting LED on the EC-14
controller. Depending upon the type of problem and its
position of occurrence the EC-14™ controller can continue
antilock function at a lower performance level, disable all of
the antilock on the vehicle or only a portion. When antilock
is disabled, the brakes on the affected axle(s) revert to
standard air braking.
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NON-ANTILOCK BRAKE APPLICATION
During normal braking, the brake valve simultaneously
delivers air to the control port of the M-12™ modulator on the
rear axle(s) as well as to and through the M-21™ or M-22
modulator on the front axle. The M-12™ modulator functions
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Complete antilock system shut down will occur if:
• Electrical power is below or above the 10 to 17 volt
operating range.
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• A controller fault is detected.
• Two or more faults, regardless of where, are detected.
• An M-12
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modulator malfunction on the rear axle(s).
• Only front axle antilock will be disabled if a problem with
the M-21™ or M-22™ modulator is detected.
A problem in a single speed sensor will not result in disabling
of the antilock system. If a speed sensor malfunction is
detected by the EC-14™ controller, the remaining speed
sensor on the axle will be used to continue antilock operation
on the axle but at a slightly degraded level of performance.
With the failed component approach described, the antilock
system will attempt to provide the vehicle with the best
possible braking and stability even after a problem has
occurred. It should be remembered that the driver will be
advised of any 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.
ANTILOCK WIRING
GENERAL NOTES
The wires that carry information and power into and out of
the EC-14™ controller are grouped and terminate at a
connector which plugs into the EC-14™ controller. 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) and
the splice made water proof.
2. Do not pierce wire insulation when checking for continuity.
Check for power, ground or continuity by disconnecting
the connector and testing the individual pins or sockets
in the connector(s).
3. Always check the vehicle handbook for wire and
connector identification. Individual wire identification will
differ depending upon the type of connectors in use, the
vehicle manufacturer, and the system features in use.
4. While the retarder disable and serial link connections (3
total) are present on all EC-14™ controllers they are not
always used.
PREVENTATIVE MAINTENANCE
GENERAL
Important: Review the warranty policy before performing
any intrusive maintenance procedures. An extended warranty
may be voided if intrusive maintenance is performed during
this period.
Because no two vehicles operate under identical conditions,
maintenance and maintenance intervals will vary . Experience
is a valuable guide in determining the best maintenance
interval for any one particular operation.
Visually check for physical damage such as broken air lines
and broken or missing parts.
Perform the tests and inspections presented at the
prescribed intervals. If the EC-14™ controller fails to function
as described, it should be repaired or replaced with a genuine
Bendix unit, available at any authorized parts outlet.
Every 3 months or 25,000 miles, or 900 operating hours:
1. Check all wiring and connectors to ensure they are
secure and free from visible damage.
2. Although the EC-14™ controller incorporates a self check
diagnostics, the LED display should be inspected to
ensure that they are functional. With the tractor ignition
on and a brake application held applied, hold a magnet
(800 gauss; capable of picking up 3 ounces) on the
Diagnostic Window Reset Switch and note all of the
LEDs illuminate. If one or more of the LEDs do not
illuminate and the antilock condition lamp on the trailer
indicates the system is functioning properly, the nonilluminated LED(s) should be noted for future reference.
Although the diagnostic capabilities will be limited, the
system will continue to function as designed.
3. Road test the trailer by making an antilock stop from a
vehicle speed of 20 miles per hour. When an antilock
stop is made, the modulator solenoids pulsate and an
audible burst of air can be heard. The wheels should
not enter a prolonged "lock" condition.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
engine be in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Use only the proper tools and observe
all precautions pertaining to use of those tools.
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FIGURE 6 - MC-14™ ANTILOCK WIRING SCHEMATIC
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