By HWH 9/23/99
MANUAL AIR LEVELING
All current HWH air leveling systems can be operated in the manual mode. This is accomplished using the RAISE (up arrow) and LOWER (down arrow) buttons on the right side of the touch panel in conjunction with the four yellow LEVEL lights. These are momentary buttons. The operation will stop when the button is released.
IMPORTANT: It should be noted at this time that this system is designed to be a computerized leveling system. Manual operation is provided for operator convenience and system diagnostics. Leveling the vehicle manually when the computer cannot level the vehicle may put the vehicle in a bind.
The ignition key should be on with the engine running. Running the engine while leveling will provide better air supply for leveling the vehicle. Remember that some systems cannot be turned on unless the ignition is in the on position. The parking brake must be set or the system will not latch in.
Push the AIR button, the AIR LEVEL light will come on steady. The four red WARNING lights will come on. The TRAVEL light will go out. One or two yellow LEVEL lights may be on. A lit yellow light indicates a side or end of the vehicle is low. When no yellow LEVEL lights are on, the vehicle is level.
IMPORTANT: With some systems and all older systems, anytime the AIR button is pushed one time the computer will monitor the use of the system. If the system is left unattended for approximately five minutes, the system will shut down and the touch panel will turn off. If the ignition is on the vehicle will return to ride height.
Always level from side to side first. If no side yellow lights are on, the vehicle may be leveled front to rear. Lowering the vehicle completely before leveling is not recommended. If the vehicle has three-point air leveling it should not be lowered before leveling. A corner of the vehicle can be raised by first raising aside then the end of the vehicle.
Pushing an up or down arrow send s a +12 volt signal to the appropriate valves. Remember current HWH air leveling systems will operate the valves as a BI-AXIS”‘system.
When leveling, push and hold the LOWER (down arrow) button opposite the lit yellow light starting with the side LEVEL lights. If a yellow light will not go out in the down mode, push and hold the RAISE (up arrow) for the yellow lights, starting with the side LEVEL lights.
If a side and front or rear yellow light are on and the side light will not go out in the down mode, but goes out after raising the low side, use the RAISE (up arrow) buttons when leveling the vehicle from front to rear. Trying to lower the ends of the vehicle when one side is completely lowered may twist the vehicle. On the front of the vehicles with 600 and 680 series leveling, if one side is completely lowered the opposite front airbags will not lower.
When manual leveling is complete, turn the ignition off. Then push the touch panel “OFF ” button. If the touch panel is turned off before the ignition, the vehicle will return to ride height. If the touch panel is not turned off, it will turn itself off and the vehicle will return to the ride height of the ignition is on. The system will NOT go into the SLEEP mode if manual leveling is used.
AUTOMATIC AIR LEVELING
The 500, 600 and 680 series leveling systems are designed to be automatic systems. The control box contains a program chip that makes decisions on how to level the vehicle when the system is in the automatic mode. The level sensing unit sends ground signals to the control box to turn yellow LEVEL lights on when aside, end or corner of the vehicle is low. The control box monitors the yellow lights and performs leveling functions accordingly.
Turn the ignition to “ON”. The engine should be running. This provides a better air supply for leveling. Some systems cannot be turned on if the ignition is not on. The parking brake must be set if the ignition is on. If the parking brake is not set the AIR LEVEL light and the NOT IN PARK light will come on while the “AIR” button is being pushed. The panel will turn off when the button is released.
Pressing the AIR button one time turns the system on. The AIR LEVEL light will be steady. The “TRAVEL” light will be out. The four red WARNING lights will be on and one or two yellow LEVEL lights may be on.
DO NOT dump all the air from the airbags at this time. Allow the system to level the vehicle from travel height.
Press the air button a second time. The AIR LEVEL light will start flashing and the system will start leveling the vehicle. If all the yellow LEVEL lights go out, the AIR LEVEL light will quit flashing and stay on steady. The system goes into a “SLEEP” mode and will maintain level until the system is turned off. If all of the yellow lights will not go out, the system will indicate EXCESS SLOPE and hold until the system is shut off.
See the following two sections for detailed explanations of the “SLEEP” mode and the “EXCESS SLOPE” mode.
All air leveling programs are based on timed sequences and the yellow LEVEL lights. An example would be in one program a lower solenoid valve has to be on for 45 seconds or the yellow light has to go out before the computer will go to the next function. Times used to perform different functions is the main difference between programs.
There are two basic leveling programs, but there can be variations of these programs. Locating the program chip number will allow you to get the exact leveling program being used.
The most common leveling program is one where we first attempt to level the vehicle by lowering the high side or end of the vehicle. The computer will always level the vehicle side to side before leveling front to rear. If a sidelight comes on during front to rear leveling, the computer will stop front to rear leveling and level the vehicle side to side. After a set amount of time, usually 45 seconds, if the yellow light will not go out in the lower mode, the system will go into a raise mode. It will put air into the airbags for the side or end of the vehicle that is low, trying to put out the yellow light by raising the vehicle. Once the system goes into the raise mode it will not return to a lower mode. The following is an example of how this program would level a vehicle:
A right side and front yellow LEVEL light are on. Dump air from the left side (high side) for 35 seconds and the right side LEVEL light goes out. The front light is still on. Dump air from the rear (high end) for 45 seconds, the front LEVEL light does not go out. Switch to raise mode. Add air to the front to raise. While adding air to the front, the right side LEVEL light comes back on. Quit the front raise and raise the right side until the right side LEVEL light goes out. Quit right side raise. Return to the front raise because the front LEVEL light is still on. After a few seconds, the front LEVEL light goes out. The vehicle is level and the system goes into the sleep mode.
The other program is designed for a vehicle that because of the weight of the rear of the vehicle and the suspension being used, side to side leveling is hard to accomplish. When the system is turned on and the computer sees a rear LEVEL light or a rear and side LEVEL light the first thing that is done is the raise solenoids for the rear are turned on and the rear of the vehicle is raised for 30 seconds. Any change in the yellow lights during this process will not affect the 30 second raise function. If either or both yellow LEVEL lights go out, the 30 second raise function will continue until complete.
After the 30-second raise function is complete, the computer will check the yellow lights and level the vehicle starting with the lower high side program.
If a side or side and front LEVEL light is on, the computer will start with the lower high side program. The lower high side program is the same as the first program that was discussed.
After an initial 30-second raise function, the system will not use a 30-second raise function again, no matter which yellow LEVEL lights are on. The computer will not use the 30-second raise function when it is in the SLEEP mode.
SLEEP MODE
The SLEEP mode is a routine that will maintain the level position of the vehicle over an extended period of time. If the vehicle is leveled, all yellow LEVEL lights go out during the automatic leveling procedure, the computer will go into a SLEEP mode. This happens automatically after all the LEVEL lights go out. The system will NOT go into a SLEEP mode if manual air leveling is done.
The SLEEP mode starts after all the yellow LEVEL lights have gone out. The computer goes to sleep. The red AIR LEVEL lights stay on steady. The ignition can be turned off. After 30 minutes, the computer wakes up. It will now stay awake and monitor the yellow LEVEL lights. Flashing LEVEL lights will not affect the computer. The computer must see a LEVEL of light on constant for one minute. If a LEVEL light comes on constant, the computer will re-Level the vehicle, starting with the original lower high side leveling routine. (A 30-second raise routine will not be used when the computer is in the SLEEP mode.) After the yellow lights go out and the vehicle is re-Ieveled, the computer goes back to sleep for 30 minutes. The computer will then wake up and begin monitoring the yellow LEVEL lights. It will continue this routine until the touch panel is turned off.
If no yellow LEVEL lights are observed by the computer, the computer stays awake and monitors the LEVEL lights. The only time the computer goes back to sleep is if the vehicle has been re-Leveled.
There is no SLEEP indicator on the touch panel that indicates the computer is asleep or awake. When the computer is awake the red AIR LEVEL light will flash very rapidly while a yellow light is lit. If a yellow light stays on constant for one minute, the AIR LEVEL light will flash slower indicating a leveling process has started.
EXCESS SLOPE
EXCESS SLOPE is a situation where a vehicle can not be leveled automatically, (all yellow lights will not go out) in a set amount of time. EXCESS SLOPE is normally 10 or 15 minutes. A few systems may allow as much as 45 minutes before going EXCESS SLOPE.
The EXCESS SLOPE time does not start until the computer starts the raise low side or end functions. EXCESS SLOPE time is not the accumulative time of all raise functions. The air solenoids for a specific raise function must be on without interruption for the specified EXCESS SLOPE time before the system will go into EXCESS SLOPE.
With older systems, the computer would go into the SLEEP mode if the system went into EXCESS SLOPE. All current programs will leave the touch panel on if the system goes into EXCESS SLOPE, but will not go into the SLEEP mode. The AIR LEVEL light and the EXCESS SLOPE light will stay on until the panel is turned off.
A few programs have a background level timer of 15 minutes. This is 15 minutes of accumulative time for all functions after the “AIR” button is pushed a second time. The system will go into the SLEEP mode not EXCESS SLOPE mode if this timer reaches 15 minutes, even if yellow LEVEL lights are still on. The EXCESS SLOPE time for this system is 10 minutes. If 10 minutes of leveling in the raise mode happen before the 15 minutes background level time expires, the system will go into EXCESS SLOPE and not go into the SLEEP mode.
“DUMP” AND “RAISE” BUTTONS
The “DUMP” and “RAISE” buttons are provided to allow the operator to raise or lower the vehicle while the vehicle is moving short distances to avoid an obstacle, such as lowering the vehicle to get into a building.
CAUTION: The vehicle should not be moved at speeds in excess of 5 m.p.h. unless the vehicle is at the proper ride height. It is the operator’s responsibility to check that the vehicle is at the proper ride height for traveling.
The “DUMP and “RAISE” buttons are on the left side of the touch panel beneath the AIR button. Each button has its own indicator light. The “DUMP” and “RAISE” buttons will work in one of two ways. With one system the buttons will be momentary, working only while being pushed. The other system allows the “DUMP and “RAISE” buttons to latch in after being pushed.
Momentary “DUMP” and “RAISE” buttons. If the system has momentary “DUMP” and “RAISE” buttons, the buttons can be used about anytime. The ignition can be on or off. The parking brake does not have to be set. The touch panel can be on or off. The only time the “DUMP” and “RAISE” buttons will not work is if the touch panel is in the automatic leveling or SLEEP mode.
When a momentary “DUMP” button is pushed, a +12 volt signal is sent to all lower solenoid valves in the system. The red AIR LEVEL light will come on steady. The red DUMP light will flash. Air will be exhausted from all the airbags lowering the vehicle. When the “DUMP” button is released, the lower solenoid valves will close. The indicator lights will go out. If the ignition is off, the vehicle will stay in the position it was when the button was released. If the ignition is on, the system will go to the TRAVEL mode and the vehicle will return to travel height. If the touch panel was on when the “DUMP” button was pushed, the touch panel will turn off when the button is released.
When a momentary “RAISE” button is pushed, a +12 volt signal is sent to all raise solenoid valves in the system. The red AIR LEVEL light will come on steady. The red RAISE light will flash. Air will be added to all the airbags, raising the vehicle. When the “RAISE” button is released, the raise solenoid valves will close. The indicator lights will go out. If the ignition is off, the vehicle will stay in the position it was when the button was released. If the ignition is on, the system will return to the TRAVEL mode and the vehicle will return to travel height. If the touch panel was on when the “RAISE” button was pushed, the touch panel will turn off when the button is released.
Latching “DUMP” and “RAISE” buttons. A system with latching “DUMP” and “RAISE” buttons must have the ignition on to function. The parking brake does not have to be set. The touch panel can be off or on. The “DUMP” and “RAISE” buttons will not work if the touch panel is in the automatic level or SLEEP mode.
Systems with latching “DUMP” and “RAISE” buttons are connected to a transmission speed switch. A +12 volt signal is supplied, to the control box if the vehicle is moving at a slow speed, usually below 15 m.p.h. When the vehicle exceeds 15 m.p.h., or whatever speed the speed switch is set at, the +12 volt signal is turned off. If the +12 volt speed switch signal is not present, the “DUMP” and “RAISE” buttons will work like momentary “DUMP” and “RAISE” buttons.
CAUTION: The “DUMP” and “RAISE” buttons should not be pushed if the vehicle speed exceeds 15 m.p.h.
When a latching “DUMP” button is pushed, a +12 volt signal is sent to all the lower solenoid valves. The AIR LEVEL light will come on steady. The red DUMP light will flash. Air will be exhausted from all the airbags lowering the vehicle. The vehicle will lower as far as it can go. The touch panel and system will stay in the DUMP mode when the button is released and the vehicle will remain in a completely lowered position. The panel will remain in the DUMP mode until the “OFF” button is pushed or until the vehicle speed exceeds 15 m.p.h. This speed may be set lower on some vehicles. The system will not return to the TRAVEL mode and the vehicle will not return to travel height until the “OFF” button is pushed or the vehicle exceeds the speed switch setting.
When a latching “RAISE” button is pushed, a +12 volt signal is sent to all the raise solenoid valves. The AIR LEVEL light will come on steady. The red RAISE light will flash. Air will be added to all the airbags raising the vehicle. The vehicle will raise as far as it can go. The touch panel and system will stay in the RAISE mode when the button is released and the vehicle will remain in a completely raised position. The panel will stay in the RAISE mode until the “OFF” button is pushed or until the vehicle speed exceeds the speed switch setting. The system will not return to the TRAVEL mode and the vehicle will not return to travel height until the “OFF” button is pushed or the vehicle exceeds the speed switch setting.