BENDIX SD-13-4785 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

ACTUATOR

REAR AXLE

™

CR-15

ASSEMBLY

™

EC-15

CONTROLLER

TANDEM AXLE

ANTILOCK

RELAY

™

AR-1

SERIAL LINK

RELAY

DASH LAMP

CONTROL

RETARDER

™

M-21

SERVICE

BRAKE VALVE

QUICK

SENSOR

WHEEL SPEED

EXCITER (4)

RELEASE VALVE

(4)

SERVICE

FRONT AXLE

CHAMBER

MODULATOR

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

2

PACKARD 30 PIN

CONNECTOR

FIGURE 3 - EC-15™ 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 modifi ed 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

3

AR-1

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

™

ANTILOCK

RELAY VALVE

EC-15™

ELECTRONIC

CONTROLLER

the service 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 confi guration 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 modifi ed 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™ ANGLED

SENSOR

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 fi rst.
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 fi gure 2)

NON-ANTILOCK BRAKE APPLICATION

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 modifi cation 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
specifi c 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™ MODULATOR

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

DELIVERY

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 fi gures 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 specifi c 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 fl ux (not acid based fl ux)
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 identifi cation. Individual wire identifi cation
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
not always used.

™

controllers they are

PREVENTATIVE 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 A VOID 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, fi ttings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifi cally 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 specifi cally 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.

11. For vehicles with Antilock Traction Control (ATC),
the ATC function must be disabled (ATC indicator
lamp should be ON) prior to performing any vehicle
maintenance where one or more wheels on a drive
axle are lifted off the ground and moving.

REMOVING THE EC-15™ CONTROLLER
ASSEMBLY

EC-15™ CONTROLLER MOUNTED ON ANTILOCK
RELAY 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

7

REAR

CONNECTOR 2

DEUTSCH CONNECTORSVEHICLE RIGHT FRONT

FRONT

CONNECTOR 1

CONNECTOR 2

TERMINAL TERMINAL CONNECTION

1J POWER

1K DASH LAMP (RELAY)

1P GROUND

™

EC-15

1N LEFT FRONT MODULATOR EXHAUST

1E LEFT FRONT MODULATOR HOLD

1M LEFT FRONT MODULATOR SOURCE

1F LEFT FRONT SPEED SIGNAL

CONTROLLER

1G LEFT FRONT SPEED SIGNAL RETURN

1B RETARDER DISABLE

™

M-21

MODULATOR

CONNECTOR 1

1C RIGHT FRONT MODULATOR EXHAUST

1A RIGHT FRONT MODULATOR HOLD

1D RIGHT FRONT MODULATOR SOURCE

1H RIGHT FRONT SPEED SIGNAL

1L RIGHT FRONT SPEED SIGNAL RETURN

2K LEFT REAR SPEED SIGNAL

2G LEFT REAR SPEED SIGNAL RETURN

2A LEFT REAR MODULATOR EXHAUST

2C LEFT REAR MODULATOR HOLD

2D LEFT REAR MODULATOR SOURCE

2M RIGHT REAR SPEED SIGNAL

2L RIGHT REAR SPEED SIGNAL RETURN

2E RIGHT REAR MODULATOR EXHAUST

2N RIGHT REAR MODULATOR HOLD

2F RIGHT REAR MODULATOR SOURCE

2B SERIAL A

2H SERIAL B

VEHICLE LEFT REAR

RELAY

SPEED SENSOR

CONTROL

DASH LAMP

RETARDER

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

8

™

HOLD

SOURCE

CONNECTOR ON M-21

EXHAUST

MODULATOR