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7/1/2024
Service Bulletin: SB2401
Issue:
It has been brought to our attention that several customers have experienced
issues attempting to deploy their attenuator and hydraulically raised arrow board. When
deploying the system, the arrow board will raise prior to the attenuator deploying. This
may be consistent or intermittent and will occur regardless of using a Royal OneTouch
or a standard two button controller. If you are experiencing the stated issue, please
reach out to your account manager prior to taking corrective action.
During a Traffix investigation of the issue, they found that the attenuator hydraulic
hoses may have been contaminated leading to valves throughout the system to not
function as intended. The following instructions will describe how to flush the system,
checking for contaminants along the way.
Number of personnel: 1-2
Tools:
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Strap (3,000lb min load rating)
Safety Glasses
Wrenches
o 3/8”
o 1/2”
o 9/16”
o 11/16”
o 3/4”
o 13/16”
o 7/8”
o 1 1/2”
1 1/2” Socket
5/32 Allen Wrench
3/16 Allen Wrench
T25 Torx
#2 Phillips Head Screwdriver
Dead Blow Hammer
Pliers
Vacuum Pump (Ex. Matco MVP5000)
Impact Gun
Safety Stairs (min Height of 4 ft)

Estimated Time: 2-3 Hours

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Flushing Instructions:
1. Prior to starting, ensure the vehicle is parked on a level surface, ideally inside of a
shop to prevent further contamination inside the system and prevent spills in the
environment. With the attenuator and arrow board in the stowed position and the
attenuator resting on the prop, strap the attenuator to the body of the truck. This
is done as a safety measure to ensure the attenuator does not fall once the
hydraulic system is disconnected.

2. Open your two-button controller using the 4 screws at the face of the controller.
Ensure the controller is not connected to the system at this point. With the wire
coming out of the bottom of the controller you should see a white wire on the left
side. Disconnect the white wire and safely cover it temporarily to prevent the pump
from being activated. Reinstall the face plate on the controller and connect it to
the attenuator at the passenger side 4 pin connector. Press and hold both buttons
simultaneously, you should hear the valve solenoids open which depressurizes the
hydraulic system. Disconnect the controller from the attenuator and reinstall the
white wire to the proper terminal.
White wire activates
pump power.
Disconnecting this allows
valves to open and the
system to decompress
without driving the pump

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3. Disconnect the attenuator power by tripping the 250amp breaker located near the
chassis battery box. As an additional step of caution, it is recommended to
disconnect the grey Anderson plug located at the passenger side at the rear of the
frame rail.

250amp Breaker
Yellow flag exposed
when tripped

Anderson Plug

4. With all mechanical, electrical, and hydraulic safety procedures in place, remove
the pump from the bottom of the attenuator. Using a T25 Torx, 3/8” and 1/2”
wrenches, disconnect wires starting with the white and black wires in any order.
Then disconnect the red and black cables. After this you can disconnect the yellow
and black wires under the cables. Once the wires are disconnected, use a 13/16”
wrench to disconnect 2 hydraulic hoses from the pump. Use 11/16” and ¾”
wrenches to remove the 2 hoses from each cylinder, mark hoses for top and bottom
of pump for reference later. Remove the pump from the frame using a 9/16” wrench
to loosen 2 bolts.
White Wire
Black Wire
(2) Black
Wire
Yellow Wire
Red Cable
Black Cable

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Bolts to
remove pump
from frame.

5. Pump remaining fluid out of pump into a container then use a #2 Phillips Head
Screwdriver to remove the screws connecting the reservoir to the pump. (Watch
all O-rings/fittings.) Make marks on pump and reservoir to ensure correct alignment
when reassembling. After screws are removed use a dead blow to ease the
reservoir off. Once removed, drain out fluid into a clear container and inspect the
inside of reservoir for contaminants. If a clear container is not available, strain the
fluid through a white shop cloth. Ensure to inspect both the reservoir and the
drained fluid for black or metallic debris. After inspection clean out inside of
reservoir. Remove and clean both valves from pump.
Clean fluid shown, no black
or metallic debris.

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Valves to be
cleaned.

Clean reservoir shown,
no black or metallic
debris

6. Beginning at the top of the attenuator, remove lines between the cylinder and
manifold using 11/16” and ¾” wrenches. Use 5/32” and 3/16” Allen Wrenches for
upper cylinders and blocks. Drain then flush hoses using a vacuum pump. Once
removed, drain and flush block and cylinders then reassemble.
When
reassembling, ensure to lubricate O-rings and use caution not to cross thread
fittings.

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7. At the bottom remove the valves and hoses from the block using 11/16” and ¾”
wrenches for the hoses and a 7/8” wrench for the valve. Remove hoses from
cylinders. Once removed use a vacuum pump to drain and flush. Use a 1 ½”
wrench and an impact gun with a 1 ½” socket to remove cylinders. Reassemble
components after flush is complete.

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8. Using the same method, repeat the flushing at the arrow board manifold. Carefully
remove the pressure valve from the manifold and clean the valve and manifold,
ensure to not adjust the set screw as it will affect the timing of the attenuator to the
arrow board.

Manifold
Valve

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9. Put reservoir and pump back together, then reinstall on pump bracket at the bottom
of the attenuator. Reconnect hoses then wiring to pump. Reference photos below.
Reconnect Anderson plug and breaker and cycle the system several times keeping
the reservoir topped off to bleed air out of the system. The cap on the reservoir
will self-bleed, there is no need to open lines downstream.