Western HTS Mechanic's Manual page 35

THEORY OF OPERATION
3-PORT MODULE ELECTRICAL
Blue Label Module
(PN 29760-2)
NOTE: Limited vehicle application.
According to the vehicle
manufacturer, all 2008 Ford Super
Duty F-250/350/450/550 trucks
built before 04/18/2007 will require
this module. Trucks built after
that date and having the Plow
Prep Package use the green label
module (PN 29070-1).
Snowplow not attached to vehicle:
System is inactive. Vehicle lighting
system functions normally.
Snowplow attached to vehicle and
the electrical connections at the
grille are made:
System is inactive until either the
vehicle ignition switch or the vehicle
parking lights are activated. Vehicle
and snowplow lighting systems
function as outlined in the Theory of
Operation Overview.
Lit. No. 41467, Rev. 01
• Turning on the vehicle ignition
switch provides 12V to the
switched accessory wire, which
in turn applies battery voltage to
the VACC input to the module
at port C, pin C. A control
circuit senses the voltage and
energizes the coil of the module
control power relay. Energizing
the coil of the control power relay
causes the relay contacts to shift
from the "N.C." (normally closed)
position to the "N.O." (normally
opened) position, which supplies
battery voltage to the snowplow
control via the plug-in harness
and the vehicle control harness.
The switched accessory wire
only controls battery voltage to
the snowplow control.
• Activating the vehicle park
light circuit applies battery
voltage to the module park
circuit input, port B, pin H. The
voltage is applied to a solid
state power device, which
causes the device to turn ON
and apply battery voltage to the
snowplow park lamp fi laments
via the vehicle and snowplow
lighting harnesses. Voltage is
also applied to the module's
high and low beam relay coils,
which causes the relay contacts
to shift from the "vehicle" to the
"snowplow" position.
• With the headlamp relays shifted
to the "snowplow" position, the
vehicle high and low beams
are now directed to the snowplow
headlamps via the vehicle and
snowplow lighting harnesses.
Toggling the dimmer switch
between high and low beam will
toggle the snowplow high and
low beams.
• Activating the turn signal
applies battery voltage to the
module turn signal circuit input.
Left: port B, position G; Right:
port C, position G. The voltage
is applied to a solid state power
device, which causes the device
to turn ON and apply battery
voltage to the snowplow turn
signal lamp fi laments via the
vehicle and snowplow lighting
harnesses.
• On vehicles equipped with
DRLs integrated into the
vehicle headlamps, activating
a switched accessory wire (a
key-controlled power source)
applies battery voltage to the
module's high and low beam
relay coils, which causes the
relay contacts to shift from the
"vehicle" to the "snowplow"
position. This module will
transfer the vehicle headlamp
DRLs to the snowplow.
April 15, 2021
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