BENDIX SD-13-4783 Manuel D’Utilisation

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WS-20
WHEEL SPEED SENSOR
Reservoir
Reservoir
SPRING 
BRAKE
SUPPLY (EMERGENCY) LINE
CONTROL (SERVICE) LINE
TO TRAILER ELECTRICAL 
CONNECTOR
SPRING BRAKE
M-12R
MODULATOR
TRAILER ANTILOCK
WIRING HARNESS
EC-13
 CONTROLLER INFORMATION 
INPUTS AND COMMAND OUTPUTS
GENERAL 
The EC-13
 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-13
 controller both receive and deliver 
commands and information.
INPUTS 
Wheel speed information is provided to the EC-13
 
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-13
 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-13
 
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-13
 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-13
 controller 
from the stop light switch.  The electrical ground for the 
EC-13
 controller is from the 7 pin trailer connector and 
trailer chassis.
OUTPUTS 
Modulators, like the Bendix
®
 M-12
 and M-12R
 
modulators, are the means by which the EC-13
 antilock 
controller is able to modify driver applied air pressure 
to the service brakes.  The EC-13
 controller is able to 
simultaneously and independently control two modulators 
assemblies.  The M-12
 and  M-12R
 modulators are 
combination valves consisting of a standard relay valve 
and solenoid assembly.  They replace the standard relay 
valves used to speed up the application and release of the 
trailer’s rear axle brakes.  An external, three pin, wiring 
harness connects the  EC-13
 controller to the M-12
 or 
M-12R
 modulator solenoid assembly.  For additional 
information and service procedures see Bendix Service 
Data Sheet SD-13-4772.
As stated previously, the EC-13
 controller is designed to 
control two modulators.  It can be mounted directly on an 
M-12
 modulator relay valve assembly and control a separate 
M-12R
 modulator or the EC-13
 controller can itself be 
remote mounted to the trailer and control two M-12R
 
modulators.  When mounted directly on a modulator, the 
two separate components (EC-13
 controller and M-12
 
modulator) become a single assembly called the MC-13
 
modulator controller.
EC-13
CONTROLLER
FIGURE 2 - TYPICAL EC-13
 TRAILER ANTILOCK SYSTEM
30 PIN CONTROLLER 
CONNECTOR
WS-20
WHEEL SPEED 
SENSOR
SR-5
SPRING BRAKE VALVE
M-12R
MODULATOR