MP24.9735
17JUN09
SECTION II
625/625S SERIES LEVELING SYSTEMS
COMPONENT INSTALLATION
The air bags can be deflated by disconnecting the air line that goes from the height control valve to the air bag. The best
access to accomplish this is probably at the height control valve. The air dump solenoid valve tees in between the height
control valve and the air bag. The kit will contain air dump solenoid valves as needed, a tee fitting for each air dump valve
and a length of 3/8 inch air line. The tee will be 3/8’ by 3/8" by 3/8". If the air line between the height control valve and the
air bag is a different size than 3/8 inch, you will have to supply the correct tee fitting. ALL AIR LINE FITTINGS USED MUST
BE DOT APPROVED. Typically, the dump valve is located fairly close to the height control valve. The valve should be
mounted solidly to some type of frame member if possible. Ample air line is supplied to move the dump valve where it can
be mounted properly. The valve has 2 mounting screws on the bottom of the valve that can be used to attach the valve to
a mounting bracket. It is best if the valve is mounted so the exhaust port is protected from road splash. This will help keep
the exhaust port free from dirt which could interfere with the operation of the valve. IT IS IMPORTANT TO KEEP THE DUMP
VALVE AND AIR LINES AWAY FROM ANY HEAT SOURCES SUCH AS THE ENGINE EXHAUST.
4.) POWER UNIT / CONTROL BOX ASSEMBLY INSTALLATION
Figure 9
Air Dump Valve by HWH
Mounting Screws
3/8" Air Line by HWH
Existing Air Bag
Existing Height
Control Valve
Tee Fitting by HWH
Existing Air Line
Before installing the power unit assembly, you should check the length of the touch panel harness and lay out the warning
switch / pressure switch harness. The power unit assembly should be mounted in a position that allows the harnesses to reach
their designated components. HARNESS SHOULD NOT BE LENGTHENED IN THE FIELD. The warning / pressure switch
harness has wires labeled for specific jacks. The plugs should not be switched front to rear or side to side. If this happens, the
system will not function properly. Also, the control box level sensing unit should be programmed before installing the power unit
assembly. See "Programming the level sensing unit" located in this section, on this page.
The power unit assembly should be mounted away from heat sources and protected from road splash. The valves must be
accessible without having to crawl under the vehicle. This allows the valve release nuts to be used to lower the vehicle safely
in the case of an electrical failure. Also consider accessibility for hose and harness routings. Mounting the assembly so the
clear cover of the control box will be visible is desirable.
The power unit assemblies designed for class C applications can have the control box with its mounting bracket removed from
the main assembly and mounted in a remote location. The amount the control box can be moved is limited to the length of the
power unit harness. The touch panel and warning/pressure switch harness lengths should be considered when moving the
control box. When remote mounting the control box, pay attention to heat sources, road spray and accessibility issues. The
control box must be mounted to a solid surface with the "This Side Up" sticker pointing up.
Programming the Level sensing unit: The level sensing unit is located in the control box. The sensing unit must be
programmed so the control box knows where the front of the vehicle is and what type of suspension is used, air or spring.
It would be best to program the sensing unit before installing the power unit assembly or the control box if it is to
be mounted separate from the power unit. The power unit assembly or control box is to be mounted in one of four
directions. The clear cover of the control box should point to the front, rear, left (driver) side or right (passenger) side of the
vehicle. HWH refers to the front of the vehicle as "North", no matter which way the vehicle is pointed. The rear is "South",
the left side is "West" and the right side is "East". The sensing unit board has 4 programming jumpers; JP1-JP2-JP3-JP4.
Jumpers 1 and 2 are for the direction of the control box; jumpers 3 and 4 are for the suspension type. Each set of pins
Figure 10
has a small jumper attached to one of the pins. Use the jumpers to connect the pin sets as necessary.
PLEXIGLAS (clear cover)
JP4
JP3
JP2
JP1
Unit
Sensing
Unit Adjusting
Hardware
Level Sensing
Control Box
POSITION
SHIPPED
MOVED
POSITION
Programming
Jumpers
