that should not happen. Did you turn the switch off in the back for the suspension? Did you do something else at the same time, like check the spare tire for air pressure?
I have info on 2003 navigator 4 wheel air suspension. Maybe similar
SECTION 204-05: Vehicle Dynamic Suspension — 4-Wheel 2003 Expedition/Navigator Workshop Manual
DESCRIPTION AND OPERATION Vehicle Dynamic Suspension The four wheel air suspension system is comprised of the following components:
- service switch
- control module
- two front height sensors
- one rear height sensor
- compressor and drier assembly (includes vent solenoid)
- air lines
- front and rear air spring and shock absorber assemblies
- four air spring solenoids
WARNING: The service switch for the air suspension system must be shut off prior to hoisting, jacking or towing an air suspension vehicle. This can be accomplished by turning off the air suspension switch located in the jack storage area in the rear of the passenger compartment. Failure to do so may result in unexpected inflation or deflation of the air springs which may result in shifting of the vehicle during these operations.
WARNING: Do not remove an air spring under any circumstances when there is pressure in the air spring. Do not remove any components supporting an air spring without either exhausting the air or providing support for the air spring to prevent vehicle damage or personal injury. Air Suspension Pneumatic Diagram
Item Part Number Description 1 5319 Air compressor and drier 2 5B322 Air line T-fitting 3 5B321 Air line union 4 — Air line Y-fitting 5 18945/5311 Air spring and solenoid
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Principles of Operation The 4-wheel air suspension (4WAS) module commands changes in vehicle height that are necessary for both the load leveling and the vertical height adjustment features.
The 4WAS load leveling feature automatically makes adjustments in vehicle height so that the vehicle is always at trim height, and that constant front-to-rear vehicle attitudes are maintained over the load range of the vehicle. Adjustments in height that are necessary to correct height differences between the vehicle left and right sides for the 4WAS system are restricted to what can be reliably achieved with three height sensors.
The height adjustment feature has three vehicle heights within a two-inch span:
Kneel height — improves the ease of entering and exiting by lowering the vehicle one inch below the trim height in the front and rear when the vehicle ignition is in the OFF or LOCK positions and the vehicle is stationary.
Trim height — normal vehicle ride position; vehicle moves to trim position when the ignition is ON, when the transmission is initially shifted to DRIVE or REVERSE mode, when all doors are closed or when speed of more than 24 km/h (15 mph) is detected.
Off-road height — improves ground clearance by raising the vehicle one inch above trim height in the front and rear when the vehicle is at 4x4 low modes and the vehicle speed is less than 40 km/h (25 mph).
The 4WAS module uses the universal bus protocol, (UBP), module communications network for sending and receiving various signals with the exception of speed, information from the three height sensors, and the air suspension service switch. For additional information about UBP, refer to Section 418-00 .
The 4WAS system holds vehicle height when any door or rear hatch is opened. The system stores front and rear vehicle height the moment any door is detected open. The system then maintains this height regardless of the addition or removal of a load. The system returns to its commanded height when all doors are closed or vehicle speed exceeds 24 km/h (15 mph).
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Air Suspension Service Switch The air suspension service switch signal is needed to wake up the 4WAS module. Without the module receiving this signal, the 4WAS system is inoperative at speeds below 24 km/h (15 mph) and will not react when the vehicle is raised or lowered. At speeds above 24 km/h (15 mph), the system will be active as if the air suspension service switch is in the ON position.
Vehicles without message center When the air suspension service switch is in the OFF position and the ignition switch is in the RUN position, a "CHECK SUSP" will appear in the RH corner of the instrument cluster.
Vehicles with message center When the air suspension service switch is in the OFF position and the ignition switch is in the RUN position, the message center will display "SUSPENSION SWITCHED OFF"
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Inspection and Verification
- Verify the customer concern.
- NOTE: If the door ajar indicator is illuminated when all doors, liftgate, and liftgate glass are closed, the air suspension will not work correctly. Repair door ajar indicator; refer to Section 413-01 .
Visually inspect for obvious signs of mechanical and electrical damage.
Visual Inspection Chart Mechanical Electrical
- Restricted suspension movement
- Excessive vehicle load
- Cut, severed, crimped air line(s)
- Unmounted height sensor(s)
- Damaged front air spring(s)
- Damaged rear air spring(s)
- Battery junction box (BJB) fuses 20 (30A), fuse 27 (5A), and fuse 111 (50A)
- Loose, corroded, or disconnected connectors
- Air suspension service switch is in the OFF position
- Damaged solenoid valve(s)
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I fthis does not help, the dealer can hook up his diagnostic equipment and download fault codes. Good luck. Please give best rating if this helps.
