BENDIX BW1742 Fascicule

The EC-12 controller houses the
electronics that regulate the antilock
system.  The EC-12 contains a diagnostic
window and a 14 pin connector.

The EC-12 mounts on the M-12 modulator
with four bolts and it is internally connected
to the solenoids by a four pin connector.
Sensors mounted at the wheel end send
wheel speed information to the EC-12
through the 14 pin connector.  If wheel lock
up is impending, the EC-12 commands the
solenoids to modulate brake chamber
pressure on the axle(s) on which the system
is installed.  The MC-12 modulator controller
receives power from the 7 pin, tractor to
trailer, connector at the nose of the trailer.
The ground connection to the EC-12 is also
from the 7 pin connector.  During start up,
when the trailer brakes and stop lights are
actuated, trailer antilock immediately runs
a self check.  The trailer status light, if so
equipped, flashes once and then goes off.
Should a problem occur, the status light
comes on and remains on.

If the status light remains on with power
applied, inspect the EC-12 for illuminated
LEDs. The status light is an optional feature
in the trailer antilock system.  If no status
light is present, the diagnostic LEDs should
be checked periodically.

Reset controller with magnet after repair.

Resistance Across Pins

1500 - 2500 ohms

(Ref. SD-13-4754)

STATUS INDICATOR

(Optional)

Back

Front

7 PIN CONNECTOR

Connector

Diagnostic
Window

Tie Wrap

Mounting

Block

Wheel Speed

Sensor

MC-12 Modulator

Controller

(Ref SD-13-4762)

3 PIN STYLE

CONNECTOR

IF INDICATOR REMAINS ILLUMINATED

SYSTEM REQUIRES SERVICE