Bendix EC-15 ANTILOCK CONTROLLER ASSY User Manual

®

Bendix® EC-15™ AntiLock Controller Assembly

SD-13-4785

MOUNTING

HOLES (4)

FIGURE 1 - EC-15™ ELECTRONIC CONTROLLER

DESCRIPTION

GENERAL

Bendix antilock systems utilizing the EC-15™ electronic
controller assembly provide full vehicle, wheel control braking
for buses, trucks, and truck tractors. By minimizing the
potential of “brake lock-up” on all wheels during aggressive
braking the vehicle retains a high degree of stability and
steerability , and in most cases vehicle stopping distance is
reduced.

In order to provide full vehicle, wheel control braking, the
EC-15™ controller assembly is used in combination with the
following components:

- Four, individual wheel speed sensors

- Four, air pressure modulator valves

- Antilock condition lamp (dash mounted)

DIAGNOSTICS

WINDOW DISPLAY

PHYSICAL

The EC-15™ controller electronics, that regulate the function
of the antilock system, are contained in a die cast aluminum
housing and are environmentally protected. 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 types of electrical connectors are currently used to
connect the EC-15™ controller assembly to the antilock
system components; a single, 30 pin, Packard Electric,
150 series “Metri-pack” or a pair of 14 pin, Deutsch, HID 30
series connectors.

1

SERVICE

REAR AXLE

ACTUATOR

™

CR-15

ASSEMBLY

™

EC-15

CONTROLLER

TANDEM AXLE

ANTILOCK

RELAY

™

AR-1

SERIAL LINK

RELAY

DASH LAMP

CONTROL

RETARDER

™

(4)

M-21

MODULATOR

QUICK

RELEASE VALVE

SERVICE

BRAKE VALVE

SERVICE

CHAMBER

FRONT AXLE

SENSOR

EXCITER (4)

WHEEL SPEED

FIGURE 2 - EC-15™/CR-15™ ANTILOCK SYSTEM

2

FIGURE 3 - EC-15

PACKARD 30 PIN

CONNECTOR

™

CONTROLLER AND CONNECTOR STYLES

DEUTSCH 14 PIN

CONNECTORS

MOUNTING

The EC-15™ controller is available in two different mounting
styles. One model is designed to be mounted on an antilock
relay valve such as the AR-1™ valve (see Service Data Sheet
SD-13-4795). The AR-1™ valve is a modified version of the
R-12™ relay valve. When the EC-15™ controller is mounted
on an antilock relay valve the resulting assembly receives a
different designation. For example when the EC-15™ antilock
controller is mounted on the AR-1™ valve the resulting
assembly is known as a CR-15™ antilock controller relay.
The other EC-15™ controller model is intended for bracket
mounting to a frame member and is not attached to an
antilock relay valve.

CONTROLLER INPUTS/OUTPUTS

The EC-15™ 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-15™ controller both receive and deliver
commands and information.

INPUTS

Wheel speed information is provided to the EC-15™ controller
via a wiring harness from individual wheel speed sensors
located at or in the vehicle wheels. Working in conjunction
with an exciter or tone ring, wheel speed sensors provide
information to the EC-15™ controller in the form of an AC
signal which varies in voltage and frequency as the speed of
the wheel increases or decreases. The EC-15™ 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-15™ controller is able to
simultaneously receive, and individually interpret, speed
signals from four wheel speed sensors.

Vehicle power is supplied to the EC-15™ controller from the
ignition switch through a fuse or circuit breaker. The electrical
ground for the EC-15™ controller is the vehicle chassis.

OUTPUTS

Modulators, like the Bendix® M-21™, are the means by which
the EC-15™ antilock controller is able to modify driver applied
air pressure to the service brakes. The modulator is an
electrically controlled air valve that is located near the service

3

™

ANTILOCK

AR-1

RELAY VALVE

™

EC-15

ELECTRONIC

CONTROLLER

FIGURE 4 - EC-15™ CONTROLLER MOUNTED ON AN AR-1™ VALVE

actuator(s) it controls and is the last air valve through which
air passes on its way to the brake actuator . A wiring harness
connects the modulator to the EC-15™ antilock controller.
Solenoid valves contained in the modulator provide the
electrical interface between the EC-15™ controller electronics
and the air brake system. The EC-15™ controller is able to
simultaneous and independently control four individual
modulator assemblies.

A dash light and its electrical relay is connected to, and
controlled by, the EC-15™ controller and serves as a means
of advising the driver of the condition of the antilock system.
A connection to the engine or transmission retarder is
provided on the EC-15™ controller which allows the EC-15

™

controller to temporarily “disable” the retarder during certain
modes of operation. While the EC-15™ controller is capable
of this function, and connections are provided, it is not always
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-15™ controller to “report”
its operating condition to a specialized, external computer
in response to certain commands it receives. The EC-15

™

controller data link configuration conforms to S.A.E. standard
J1708 and the protocol, or coded language used, conforms
to S.A.E. standard J1587. There are two connections to the
EC-15™ controller devoted to the data link. While the EC-15

™

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-15™ controller to be functional.

4

OPERATION

GENERAL

The Bendix® EC-15™ antilock controller system provides
individual wheel control by using a wheel speed sensor and
modulator at each wheel. By monitoring the rate of
deceleration during braking, and subsequently adjusting the
brake application pressure at each wheel, the EC-15
controller is able to provide improved braking between the
vehicle tire and the road surface it is on, while maintaining
vehicle stability .

The rear axle brakes are controlled completely independent
of each other and therefore brake application pressure at
an individual wheel is adjusted solely on the basis of its
behavior on the road surface on which it is traveling. While
each steering axle brake is under the control of an individual
modulator, the EC-15™ controller does not treat these brakes
totally independent of each other. The EC-15™ controller
utilizes a modified individual control philosophy for the steering
axle brakes. This is done in order to minimize “steering wheel
pull” in the event each wheel is traveling on a different road
surface (e.g.; ice close to the curb and a dry crown).
Essentially the EC-15™ controller controls the braking force
differences between the two brakes. The wheel on dry
pavement is initially given less braking force and is brought
up to optimum during the stop, while the wheel on ice
attempts to maintain optimum braking during the entire stop.

™

WS-20

SENSOR

™

SPEED

EXCITER RING

(100) TOOTH

HUB ASSEMBLY

WS-20

SENSOR

™

ANGLED

WS-20

™

STRAIGHT

SENSOR

FIGURE 5 - WS-20™ WHEEL SPEED SENSORS

In the case of vehicles equipped with tandem rear axles
(6x2, 6x4), the wheel speed sensors are installed at the
wheels on the axle that is most likely to lose traction first. A
single modulator controls both curb side brakes on the
tandem, and another modulator controls both brakes on the
driver’s side of the tandem. With this arrangement of the
speed sensors and modulators, both brakes on one side of
the tandem are treated as one since they will most likely be
on the same type of road surface. (Refer to figure 2)

NON-ANTILOCK BRAKE APPLICA TION

During normal braking, air pressure from the brake valve
enters the control port of the service relay valve (either an
antilock or standard relay). The service relay delivers air
to, and through, the antilock modulator located near the
braked wheel, and into the brake actuator. The service brakes
are thus applied. If the wheel sensors do not detect an
impending wheel lock up, the EC-15™ controller does not
initiate any corrective action and the vehicle comes to a
stop in a normal fashion.

DEUTSCH

CONNECTOR

PACKARD

CONNECTOR

ANTILOCK CONTROLLED BRAKE
APPLICATION SYSTEM FULLY OPERATIONAL

If a service brake application is made and the wheel speed
sensors detect an impending wheel lockup, the EC-15
controller will immediately begin modification of the brake
application using the antilock modulator(s) at the affected
wheel(s).

Solenoid valves contained in the modulator are energized
and de-energized by the EC-15™ 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 reapplication of air pressure to the brake
actuator. The solenoids in each modulator are controlled
independently by the EC-15™ controller. By opening and
closing the solenoid valves in the appropriate modulator, the
EC-15™ controller is actually simulating what the driver does
when he “pumps the brakes”. It must be remembered however
that unlike the driver, the EC-15™ controller is able to “pump”
each brake on the vehicle independently and with far greater
speed and accuracy .

™

5

SUPPLY

SOLENOID

CONNECTOR

SUPPLY

MOUNTING

HOLES

EXHAUST

FIGURE 5 - M-21™ MODULA TOR

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

DELIVERY

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.

6

2. Do not pierce wire insulation when testing. Check for
power, ground or continuity by disconnecting the
connector and testing the individual pins or sockets in
the connector.

3. Always check the vehicle hand book 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-15

™

controllers they are not

always used.

PREVENT A TIVE MAINTENANCE

Every 3 months; 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-15™ controller incorporates a self check
diagnostics, the LED display should be inspected to
ensure that they are functional. With the vehicle ignition
on, a magnet (800 gauss; capable of picking up 3 ounces)
held to the LED reset switch should cause all of the
LED’s to illuminate. If one or more of the LED’s DO NOT
ILLUMINA TE and the antilock condition lamp on the dash
indicates the system is functioning properly, the
non-illuminated 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 vehicle by making 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 from outside of the cab.
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.

4. If the work is being performed on the vehicle’s air
brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure from
all reservoirs before beginning

ANY work on the
vehicle. If the vehicle is equipped with an AD-IS
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.

5. Following the vehicle manufacturer’s
recommended procedures, deactivate the electrical
system in a manner that safely removes all
electrical power from the vehicle.

6. Never exceed manufacturer’s recommended
pressures.

7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.

8. Use only genuine Bendix

®

replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.

9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.

10. Prior to returning the vehicle to service, make
certain all components and systems are restored

to their proper operating condition.

REMOVING THE EC-15™ CONTROLLER
ASSEMBLY

EC-15™ CONTROLLER MOUNTED ON ANTILOCK RELA Y
VALVE

1. Identify and remove all air lines connected to the unit.

2. Disconnect the electrical connector(s) from the EC-15

controller.

3. Note and mark the mounting position of the controller/

relay valve assembly on the vehicle. Loosen, remove
and save the nuts on the mounting hardware that
attaches the controller relay assembly bracket to the
vehicle. Remove the relay valve and EC-15™ controller
assembly from the vehicle.

4. Remove as much contamination as possible from the

exterior of the assembly making sure to keep the
contamination away from the open ports.

5. Note and mark the position of the EC-15™ controller

relative to the antilock relay valve. Remove and retain
the four cap screws that secure the EC-15™ controller
to the antilock relay valve. Carefully separate the EC-15
controller from the antilock relay valve making certain
not to damage the gasket between the two components.
Peel the gasket from the EC-15™ controller or antilock
relay valve and retain for reuse. Note: Use a new gasket
if damaged during removal or if a new gasket is
immediately available.

™

™

™

7

REAR

CONNECTOR 2

DEUTSCH CONNECTORSVEHICLE RIGHT FRONT

FRONT

CONNECTOR 1

1J POWER

TERMINAL TERMINAL CONNECTION

CONNECTOR 2

1K DASH LAMP (RELA Y)

1P GROUND

™

EC-15

1N LEFT FRONT MODULA TOR EXHAUST

1F LEFT FRONT SPEED SIGNAL

1E LEFT FRONT MODULATOR HOLD

1M LEFT FRONT MODULAT OR SOURCE

CONNECTOR 1

CONTROLLER

1B RETARDER DISABLE

1C RIGHT FRONT MODULA TOR EXHAUST

1G LEFT FRONT SPEED SIGNAL RETURN

™

1A RIGHT FRONT MODULATOR HOLD

1L RIGHT FRONT SPEED SIGNAL RETURN

1D RIGHT FRONT MODULA TOR SOURCE

1H RIGHT FRONT SPEED SIGNAL

2K LEFT REAR SPEED SIGNAL

2A LEFT REAR MODULATOR EXHAUST

2C LEFT REAR MODULA TOR HOLD

2G LEFT REAR SPEED SIGNAL RETURN

2D LEFT REAR MODULA TOR SOURCE

M-21

MODULATOR

2L RIGHT REAR SPEED SIGNAL RETURN

2M RIGHT REAR SPEED SIGNAL

2F RIGHT REAR MODULATOR SOURCE

2E RIGHT REAR MODULATOR EXHAUST

2N RIGHT REAR MODULA TOR HOLD

2B SERIAL A

2H SERIAL B

VEHICLE LEFT REAR

RELAY

SPEED SENSOR

CONTROL

DASH LAMP

RETARDER

FIGURE 7 - WIRING SCHEMA TIC FOR EC-15™ CONTROLLER WITH DEUTSCH CONNECTORS

8

™

HOLD

ON M-21

SOURCE

CONNECTOR

EXHAUST

MODULATOR