Western HTS Mechanic's Manual page 41

THEORY OF OPERATION
4-PORT MODULE
ELECTRICAL
Snowplow Headlamps
The isolation module acts as an
electrical hub, automatically directing
vehicle power to the appropriate
vehicle or snowplow lighting devices,
while also supplying battery power to
the snowplow control.
The vehicle high and low beams
enter and exit the isolation module
through positions 3 (left-side lighting)
and position 4 (right-side lighting).
Park, turn, and DRL signals also
enter through positions 3 and 4. The
output of the vehicle dimmer switch
is directed to the isolation module via
the long and short plug-in harnesses.
All snowplow lighting exits the
isolation module through position 2.
When the snowplow is not attached
to the vehicle, the signal passes
through the normally closed relay
contacts to the vehicle headlamps.
During this time, the isolation module
is inactive, placing no current draw
on the vehicle's electrical system.
Lit. No. 41467, Rev. 01
With the snowplow attached, the
isolation module is still inactive until
either of the two following conditions
are met: The vehicle parking lights
are turned ON or the vehicle ignition
switch is turned ON.
Turning ON the vehicle parking
lights activates a series of relays,
automatically transferring the vehicle
high and low beams to the snowplow
while supplying battery power directly
to the snowplow parking lights.
Turning ON the vehicle ignition
switch energizes a snowplow control
relay, supplying vehicle battery
power directly to the control via the
vehicle control harness. The vehicle
ignition switch also supplies power
to the vehicle turn signals. Activating
the vehicle turn signals energizes
turn signal relays, which supply
vehicle battery power directly to the
snowplow turn signals.
41
April 15, 2021