MP85.9975
01SEP15
625 TROUBLE SHOOTING GUIDE
GLOSSARY
LEVEL SENSING UNIT:
NOTE:
The level sensing unit controls the yellow LEVEL indicators on the touch
The level sensing unit has a tolerance for leveling. The vehicle may not always be 100%
level and may level somewhat differently when the vehicle is parked in different places. The
vehicle should be within 3 to 4 inches front to rear and 1 inch side to side when all yellow level
lights are out.
MANIFOLD HYDRAULIC: The hydraulic manifold is mounted on top of the pump. The manifold
distributes the hydraulic fluid to the jacks as needed to extend the jacks. When retracting jacks
the fluid returns to the pump through the manifold. The maifold consists of four solenoid valves,
a pair of check valves for each solenoid valve, a 50 p.s.i. pressure switch, a 3000 p.s.i. pressure
switch and a shuttle valve. The replaceable parts of the manifold are the solenoid valves, the
pressure switches and the shuttle valve. If it is determined a check valve is bad, it may be
required to replace the complete manifold. Contact HWH when check valve problems occur.
PRESSURE SWITCH - 50 P.S.I. MANIFOLD: This pressure switch is a single wire, normally open
switch. It is mounted on the leveling system hydraulic manifold. The contacts of this switch will
close when the pressure in the manifold reaches 50 p.s.i. When the contacts of the switch close,
this supplies a ground signal to the control box. The solenoid valves that control the jacks will
not open until the control box sees the ground signal from the 50 p.s.i. switch. Without this
ground signal, the pump will run under load and no jacks will extend. This switch will not
interfere when retracting jacks.
PRESSURE SWITCH - 3000 P.S.I. MANIFOLD: This pressure switch is a single wire, normally open
switch. It is mounted on the leveling system hydraulic manifold. The contacts of this switch will
close when the pressure in the manifold reaches 3000 p.s.i. When the contacts of the switch
close, this supplies a ground signal to the control box. During the leveling mode, if a yellow
level light is on and this switch closes, the control box will turn the "EXCESS SLOPE" light that
is on the touch panel on. The panel will turn off with the "EXCESS SLOPE" light remaining on.
The "EXCESS SLOPE" light will be on whenever the ignition is on until the jacks are completely
retracted with the "STORE" button or the park brake is released with the ignition on.
PRESSURE SWITCH - JACK: This pressure switch is a single wire, normally open switch. There is
one mounted on each jack. The contacts of this switch close when the pressure the switch is
set at is reached. The contacts of this switch, when closed, supply a ground signal to the control
box. Smaller jacks and replacement switches are set at 140 p.s.i. Larger jacks will be set at a
higher pressure. The switches can be adjusted as necessary. The jack pressure switches are
used to stabilize the vehicle during the automatic leveling procedure. The jack pressure switches
should be adjusted so each jack lifts the vehicle between 1/4 to 3/4 inch after reaching the ground
when used to stabilize the vehicle.
NOTE: All hydraulic pressure switches supplied by HWH at this time are manufactured be HWH.
These switches all look the same. The switches can be identified by a tag near the Packard
connector on the switch wire. The switch part number and the set pressure are listed on the tag.
panel. The sensing unit is mounted in the control box. The sensing unit must be programmed
for the mounting direction of the control box and the type of suspension, air or spring. The
sensing unit is equipped with four sets of pins with jumpers. These are used to program the
sensing unit. There is a detailed instruction sheet available for programming the sensing unit.
The sensing unit has six wires. There is a red +12 volt supply wire on one end of the MTA
plug and a white ground wire on the other end of the plug. The red power wire is hot when the
ignition is in the ON or ACC. position. The center four wires supply a ground signal to turn a
yellow LEVEL light on when that side or end of the vehicle is low. The yellow wire is for the left
side light, the black wire is for the front light, the green wire is for the right side light and the red
wire is for the rear light. The sensing unit can be replaced if needed.
SHUTTLE
VALVE
