Bendix Commercial Vehicle Systems EC-80 ABS ATC SD - Manual (Page 4)

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PLC controller and the Bendix EC‑80 ATC controller (12
volt versions) support PLC communications in accordance
with SAE J2497.
Identifying a Bendix EC-80 Controller with PLC
Refer to the information panel on the ECU label to see if
the controller provides PLC.
An oscilloscope can be used to measure or identify the
presence of a PLC signal on the power line. The PLC
signal is an amplitude and frequency‑modulated signal.
Depending on the filtering and load on the power line,
the PLC signal amplitude can range from 5.0 mVp‑p
to 7.0 Vp‑p. Suggested oscilloscope settings are AC
coupling, 1 volt/div, 100 µsec/div. The signal should be
measured at the ignition power input of the Bendix EC‑80
controller.
Note: An ABS trailer equipped with PLC or a PLC
diagnostic tool must be connected to the vehicle in order
to generate a PLC signal on the power line.
To confirm if a specific ECU uses PLC or not, see the
Controller Specifications box below.
BENDIX EC-80 CONTROLLER INPUTS
Battery and Ignition Inputs
The ECU operates at a nominal supply voltage of 12 or
24 volts, depending on the ECU. The battery input is
connected through a 30 amp fuse directly to the battery.
The ignition input is applied by the ignition switch through
a 5 amp fuse.
Ground Input
The Bendix EC‑80 controller supports one ground input.
See pages 35-37 for electrical system schematics.
ABS Indicator Lamp Ground Input
Bendix EC‑80 ECUs require a second ground input (X1‑12)
for the ABS indicator lamp. The X1 wire harness connector
contains an ABS indicator lamp interlock (X1‑15), which
shorts the ABS indicator lamp circuit (X1‑18) to ground if
the connector is removed from the ECU.
Bendix ® WS-24 ™ Wheel Speed Sensors
Wheel speed data is provided to the Bendix EC‑80 controller
from the Bendix ® WS‑24 ™ wheel speed sensor (see Figure
2). Vehicles have an exciter ring (or “tone ring”) as part of
the wheel assembly, and as the wheel turns, the teeth of
the exciter ring pass the wheel speed sensor, generating
an AC signal. The Bendix EC‑80 controller receives the
AC signal, which varies in voltage and frequency as the
wheel speed changes.
Vehicle axle configurations and ATC features determine
the number of Bendix WS‑24 ™ wheel speed sensors that
must be used. A vehicle with a single rear axle requires
four wheel speed sensors. Vehicles with two rear axles
can utilize six wheel speed sensors for optimal ABS and
ATC performance.
Diagnostic Blink Code Switch
A momentary switch that grounds the ABS indicator lamp
output is used to place the ECU into the diagnostic blink
code mode and is typically located on the vehicle’s dash
panel.
ABS OFF-ROAD SWITCH AND INDICATOR
LAMP OPERATION
The ABS off-road mode should not be used on normal,
paved road surfaces because vehicle stability and
steerability may be affected. When the ECU is placed
in the ABS off-road mode, the ABS indicator lamp will
flash constantly to notify the vehicle operator that the
off-road mode is active.
Bendix EC‑80 ATC controllers use a dash‑mounted switch
to place the ECU into the ABS off‑road mode. In some
cases, ECUs may also be put into the ABS off‑road mode
by one of the other vehicle control modules, using a J1939
message to the Bendix EC‑80 controller.
If you need to know if a specific ECU uses a J1939 message
to operate the lamp, see the Controller Specifications box
below.
Stop Lamp Switch (SLS)
Bendix EC‑80 ATC ECUs monitor the vehicle stop lamp
status. Certain vehicle functions, such as ATC and All‑
Wheel Drive (AWD), use the status of the stop lamp to know
the driver’s intention. This can be provided to the ECU via
J1939 communications or hardware input.
BENDIX EC-80 CONTROLLER OUTPUTS
Bendix ® M-32 ™ , M-32QR ™ and M-40X ™ Pressure
Modulator Valves (PMV)
The Bendix M‑32, M‑32QR and M‑40X pressure modulator
valves (PMV) are operated by the Bendix EC‑80 controller
to modify driver applied air pressure to the service brakes
during ABS or ATC activation (See pages 6‑8). The PMV
is an electro‑pneumatic control valve and is the last valve
that air passes through on its way to the brake chamber.
The modulator hold and release solenoids are activated
to precisely modify the brake pressure during an antilock
braking event. The hold solenoid is normally open and the
release solenoid is normally closed.
Controller Specifications: If you need to know exact information about an ECU e.g. if it uses PLC, serial
communications, etc., e-mail [email protected], specifying the ECU part number, or call:
1-800-AIR-BRAKE, 1-800-247-2725, option 2, then 1, and speak to the Bendix TechTeam.