Lit. No. 28270, Rev. 00
July 1, 2005
34
THEORY OF OPERATION
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.
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.
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. All
snowplow lighting exits the Isolation
Module through position 2.
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.
SNOWPLOW DAYTIME
RUNNING LIGHTS
Because Daytime Running Lamps
(DRLs) are controlled differently on
some vehicles, two Isolation Modules
have been developed.
The standard Isolation Module
transfers the DRL output to the
snowplow lights when the vehicle
ignition switch is on and the
snowplow is attached.
When the Isolation Module designed
for vehicles with dedicated DRL
bulbs senses the vehicle in the DRL
mode, a series of relays energize,
placing the snowplow high beams in
series. This Isolation Module does
not turn off the vehicle DRLs.
SNOWPLOW HYDRAULICS
The MVP
®
snowplow hydraulic
system performs 10 blade
movements.
All movements require the vehicle
ignition (key) switch to be in the run
or accessory position and the power
to be activated on the snowplow cab
control.
Nine of the ten hydraulic movements
require energizing the electric motor,
shifting solenoid cartridge spools, or
activating P/O check valves. The
tenth function, lower, does not
energize the motor but requires
shifting solenoid cartridge spools.
Power from the vehicle battery is
supplied to the solenoid coils and the
snowplow control via the Isolation
Module. The solenoid cartridge
valves operate in various
combinations, directed by the cab
control, to send hydraulic fluid to the
snowplow lift and angle rams or back
to the reservoir.
MOVEMENT
BLADE
RAISE
LOWER
ANGLE
RIGHT
ANGLE
LEFT
RIGHT
EXTEND
RIGHT
RETRACT
LEFT
RETRACT
SCOOP
VEE
EXTEND
LEFT
