Lit. No. 41298, Rev. 01 February 15, 2019
31
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.
• 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.
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