Theory Of Operation - Western HTS Mechanic's Manual

THEORY OF OPERATION

3-PORT MODULE ELECTRICAL
White Label Non-DRL
Module (PN 29060)
NOTE: Module has been replaced
by PN 29070-1
Snowplow not attached to vehicle:
System is inactive. Vehicle lighting
system functions normally. Reason:
No ground to module.
Snowplow attached to vehicle:
System is inactive until either the
switched accessory wire or the vehicle
parking lights are activated. Vehicle and
snowplow lighting systems function
as outlined in the Theory of Operation
Overview. Reason: ground path is
established from battery common to
pin C on port A of the 3-port module
via the following harnesses: vehicle
battery cable, vehicle control
harness, plug-in harness, vehicle
lighting harness and snowplow
lighting harness.
Lit. No. 41467, Rev. 01
• Activating a switched accessory
wire (a key-controlled power
source) applies battery voltage
to the VACC input of the module,
which energizes the coil of the
control power relay (part of the
3-port module). Energizing the
coil of the control power relay
causes the relay contacts to shift
from the "N.O." (normally opened)
position to the "N.C." (normally
closed) 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.
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 four 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.
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—either integrated into the
vehicle headlamps or separated
into dedicated DRL lamps—this
module will not turn OFF the
vehicle DRLs or transfer them
to the snowplow. DRLs will
remain illuminated on the vehicle
and operate as the vehicle
manufacturer intended.
April 15, 2021
33