HWH® SYSTEM-SPECIFIC OPERATION

 LEVELING SYSTEMS – 725 SERIES

“HOW IT SHOULD OPERATE”

(Filename:  MI16_OP_LESY02.DOC  |  Revised:  14FEB17)

 

 

 

 

 

Auto Level:

 

1. Set the park brake. If the park brake is not set, the NOT IN PARK/BRAKE touch panel light will come on while the AUTO LEVEL button is being pushed.

 

2. Ignition key must be in the ACC or ON position. If in the ACC position, the master jacks down warning light and buzzer will not be on during leveling.

 

3. Push the AUTO LEVEL button one time. The AUTO LEVEL light will start flashing and continue to flash until the leveling process is complete. One or two yellow level lights may be lit, never opposing lights.

 

4. The system turns on the dump output. This output remains on during the complete leveling procedure. The pilot air dump valve puts the individual height control dump/travel valves in the dump position. The system starts dumping air from the suspension air bags and the vehicle begins to lower. The system will dump air approximately 25 seconds before the leveling procedure starts.

 

5. The pump will come on, the appropriate jack solenoid valves will be opened, the isolation valve will be opened and the system will level the vehicle according to any lit yellow level light(s). Lit yellow level lights indicate that side, end or corner is low. The system will always extend two jacks at the same time. The system will always extend jacks to turn out a lit side yellow level light before extending front or rear jacks to turn out a front or rear yellow level light. As a jack extends approximately ½ inch, the magnetic reed switch in the jack down warning switch closes completing a ground circuit and its corresponding red jack down touch panel warning light will come on. The master jacks down warning light and buzzer will only come on if the ignition is in the ON position.

 

6. When all the yellow level lights are off, there is a 2 second pause with the pump off. Then the system will stabilize the vehicle. The pump may cycle on and off during the stabilizing procedure. Each jack has a normally open pressure switch that completes a ground circuit. This switch will be on if the jack is on the ground lifting the vehicle. The system only looks at these switches during the stabilize procedure. There is a specific sequence for stabilizing. The system first looks at the right rear pressure switch. If the right rear jack pressure switch is on when checked, the system moves immediately to the left rear jack pressure switch. If the switch is off, the system runs the pump, opens the right rear solenoid valve, the isolation valve and extends the jack until the pressure switch comes on. The system then moves to the left rear jack pressure switch. The left rear jack is extended as necessary if the pressure switch is not on. When the system sees the left rear pressure switch, it returns to the right rear, rechecks that switch, extends the right rear more if necessary or if the switch is still on, goes back to the left rear and rechecks that switch, extending the left rear jack more if necessary. The system then looks at both front jack pressure switches. If either front pressure switch is NOT on, the system opens both front solenoid valves and the isolation valve. The front jacks will extend until the system sees both front jack pressure switches. If one of the front jacks is already on the ground, that jack will not move due to the check valve arrangement in the leveling system manifold.

 

7. When all four jack pressure switches are on, the pump shuts off and the AUTO LEVEL light turns off.   

 

Note: The isolation valve opens for any leveling function that requires the pump to run. It does not open when retracting jacks, auto or manual. It is only present on vehicles equipped with the HWH step.

 

EXCESS SLOPE: The EXCESS SLOPE touch panel light will only come on in the AUTO LEVEL mode. The leveling manifold has a normally open 3,000 psi pressure switch. This pressure switch contacts will close if two jacks reach full extension and a yellow level light is still on. The switch sends a ground signal to the pump I/O module. The module informs the processor there is an excess slope situation. The processor stops the leveling process and turns all loads off. The system will not stabilize the vehicle. One or two jacks may not be on the ground. The EXCESS SLOPE light will come on for two minutes then go out. All touch panel buttons will function except the AUTO LEVEL button if the EXCESS SLOPE light is on. 

 

Auto Store:

 

1. The park brake does not have to be set to use the STORE button. If the park brake is not set when the STORE button is pushed, the NOT IN PARK/BRAKE touch panel light will come on and stay on until the STORE light goes out.

 

2. The ignition must be in the ACC or ON position. (Or the engine should be started) If the ignition is in the ON position, the master jacks down warning light and buzzer will be on until all the touch panel individual red jacks down warning lights are out.

 

3. Push the STORE button. The STORE light will start flashing.

 

4. The travel output is turned on and the pilot valve switches the individual height control dump/travel valves into the travel position. If there is air in the suspension air tanks, the vehicle will start to rise to travel height. The travel output is on anytime the ignition is on and the park brake is released.

 

5. The same time the travel relay is turned on, the front solenoid valves are turned on. The front jacks will start to retract. The pump does NOT run during the store sequence.

 

6. Five seconds after the front solenoid valves are turned on, the rear solenoid valves are turned on. The rear jacks will start to retract.

 

7. As a jack retracts within approximately ½ inch of being fully retracted, the magnetic reed switch in the jack down warning switch opens and the corresponding red jack down warning light will go out.

 

8. When all four red jack down warning lights are off, the master warning light and buzzer will turn off.

 

9. One minute after the last red jack down warning light goes out, the STORE light will turn off and all the jack solenoid valves will turn off. If the NOT IN PARK/Brake light was on, it will also turn off.

 

Note: If any red jack down warning light remains on, the system will remain in the store mode with all of the jack solenoid valves will cycle for 10 minutes on then 10 off for approximately 50 minutes (or until the last red warning light goes out) and then turn off regardless of any red warning lights remaining on.

 

10. The ignition key can now be turned off.  

 

Manual Leveling:

 

1. Set the park brake. The NOT IN PARK/BRAKE touch panel light will come on while an UP arrow button is being pushed. The light will go out when the button is released. The pump will not run if the NOT IN PARK/BRAKE light is on.

 

2. Ignition key must be in the ACC or ON position. If any jacks are extended and the ignition is in the ON position, the master jacks down warning light and buzzer will be on. One or two yellow level lights may be on but never opposing yellow level lights. Lit yellow level lights indicate the side, end or corner of the vehicle is low.

 

3. Push the DUMP button. The AUTO LEVEL light will be on solid while the DUMP button is being pushed and go out when the DUMP button is released. The system turns on the dump output. This output remains on only while the DUMP button is being pushed. The button is momentary and does not have to be held on while the air is dumping. The pilot air dump valve puts the individual height control dump/travel valves in the dump position. The system starts dumping air from the suspension air bags and the vehicle begins to lower. Wait until the vehicle stops lowering.

 

3. Push an UP arrow button corresponding to a lit yellow level light. The AUTO LEVEL light will be on solid while the UP arrow button is being pushed and go out when the UP arrow button is released. The pump will run, the corresponding jack solenoid valves will be turned on and the isolation valve is turned on. Hold the UP arrow button on until the corresponding yellow level light goes out. If two yellow level lights are lit, push the side UP arrow button corresponding to the lit side yellow level light until that side yellow level light is out. Then push the front or rear UP arrow button if that yellow level light is still lit. Hold that UP arrow button on until the corresponding yellow level light goes out. As a jack extends approximately ½ inch, the magnetic reed switch in the jack down warning switch closes completing a ground circuit and its corresponding red jack down touch panel warning light will come on. The master jacks down warning light and buzzer will only come on if the ignition is in the ON position.

 

4. When all four yellow level lights are off, if both front jacks are not on the ground, push the front UP arrow button until both front jacks are on the ground and lifting very slightly.

 

5. If both rear jacks are not on the ground, push the rear UP arrow button until both rear jacks are on the ground and lifting very slightly.

 

The ignition key can now be turned to OFF

 

Manual Retract/Store:

 

1. Set the park brake. The NOT IN PARK/BRAKE touch panel light will come on while a DOWN arrow button is being pushed. The light will go out when the button is released.

 

2. Ignition key must be in the ACC or ON position. (Or the engine can be started.) If any jacks are extended and the ignition is in the ON position, the master jacks down warning light and buzzer will be on.

 

3. Push and hold the front DOWN arrow button. The AUTO LEVEL light will be on solid while the DOWN arrow button is being pushed and go out when the DOWN arrow button is released. The pump will not run. The two front jack solenoid valves will come on and the two front jacks will retract. If the DOWN arrow button is released, the valves will close and the jacks will stop retracting. Hold the button for several seconds after the two front red jack down warning lights go out. As a jack retracts within approximately ½ inch of being fully retracted, the magnetic reed switch in the jack down warning switch opens and the corresponding red jack down warning light will go out.

 

4. Push and hold the rear DOWN arrow button. The pump will not run. The two rear jack solenoid valves will come on and the two rear jacks will retract. If the DOWN arrow button is released, the valves will close and the jacks will stop retracting. Hold the button for several seconds after the two rear red jack down warning lights go out. As a jack retracts within approximately ½ inch of being fully retracted, the magnetic reed switch in the jack down warning switch opens and the corresponding red jack down warning light will go out.

 

Note: The isolation valve will not turn on when jacks are being retracted.

 

5. The vehicle will not return to ride height until the STORE button is pushed or the park brake is released. The ignition must be in the ON or ACC position for the vehicle to return to ride height. The travel output is turned on and the pilot valve switches the individual height control dump/travel valves into the travel position. If there is air in the suspension air tanks, the vehicle will start to rise to travel height. The travel output is on anytime the STORE button has been pushed and the ignition is on or if the ignition is on and the park brake is released.

 

6. The ignition key can now be turned off.

 

Component information:

 

  • Jacks – Single-acting with various mountings and lifting capabilities. Pressure extend with spring retract.
  • Jack pressure switch – Normally open, switches ground and is adjustable. 180 psi to 300 psi. (approximate)
  • Jack down warning switch – Magnetic reed switch, contacts closed with jack extended. Switches ground.
  • Solenoid valves (all) – Normally closed, +12 volt activated. All solenoid valves are equipped with flipper/cam release lever for manual operation.
  • Manifold pressure switch 3,000 psi – Normally open, switches ground. Used only for excess slope.
  • Manifold pressure switch 50 psi – Normally open, switches ground. Used to delay solenoid valves.
  • Pump – 3,500 psi relief.
  • Pump motor – Controlled with +12 volts, internally grounded.
  • Master relay – Continuous duty, 4 post, +12V controlled –

 

Vehicle with step: on only if needed to perform a function or if the ignition is on and the park brake is off.

 

Vehicle without step: on any time the ignition is in the ON or ACC position OR if a HWH  slide-out control switch is being pushed to EXTEND or RETRACT.

 

  • Pump relay – Intermittent duty, 4 post, +12V controlled – on anytime the pump is required to run.