Question about 2003 Hummer H2

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My h2 05 hummer rear air suspension will not lower, only stays in raised position.

Posted by Anonymous on

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6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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Posted on Jan 02, 2017

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  • 2 Answers

SOURCE: service air suspension

Your airbags probably have an air leak or are just starting to crack. Go to you tube and type in Suncore hummer suspension air bag replacement. They have a whole how to install that also show your suspension and how it fails

Posted on Mar 13, 2009

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ancdlm
  • 58 Answers

SOURCE: I just installed new air bags for rear suspension

It sounds to me like your compressor got killed. What probably happened is that the airbag got a hole or tiny crack in it so the compressor has to work extra hard because it is like blowing up a balloon with a hole in it. Therefor the airbag killed the compressor. I would recommend going to strutmasters.com and taking a look at our conversion kits. these convert you from the airbag to a powder coated American made steel coil spring that is guaranteed to last the life of the car. I added the link below so you can check it out.
http://www.strutmasters.com/hummer-suspension-parts-s/96.htm I hope I was of some help
Good Luck!!!

Posted on May 06, 2009

ancdlm
  • 58 Answers

SOURCE: Air Suspension service for a Hummer H2 2003

Replacing with new airbags for the Hummer will be expensive because it is not a permanent fix. I Would go with springs. I understand people enjoying the air ride but I promise it is more trouble than it is worth. Compressors have a 100% failure rate. What will happen is the airbag will end up getting a hole or tiny crack in it so the compressor has to work extra hard because it is like blowing up a balloon with a hole in it. Therefor the airbag kills the compressor and you have to parts you have to constantly keep buying. With air suspension there is never a permanent fix. I would recommend going to strutmasters.com and taking a look at the conversion kits. these convert you from the airbag to a powder coated American made steel coil spring that is guaranteed to last the life of the car. And for a very affordable cost. I added the link below so you can check it out. http://www.strutmasters.com/hummer-suspension-parts-s/96.htm Hopefully this will help Good Luck!!!

Posted on May 07, 2009

  • 1 Answer

SOURCE: Cost for servicing the air suspension on H2

i bought a new complete pump tray with all controls from red neck auto parts online for $650.00 new 1 year warranty

Posted on Aug 01, 2009

abdoush
  • 12 Answers

SOURCE: Hummer H2 SUT DTC Code C0563

u need to change/service the air compressor in ur car.
or it might be the air bags/sensors thats located next to the rear tires.

Posted on Sep 08, 2009

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2 Answers

My h2 hummer air suspension will not raise in the back both sides are down


replace air bags.200 bucks a piece, olny takes bout twenty minutes

May 16, 2011 | 2003 Hummer H2

2 Answers

What happens if the air suspension switch is turned off


If nothing is leaking the air suspension will stay in its current position. The switch is primarily used when your vehicle is service on a non drive ion rack. Failure to turn off the air ride before raising the vehicle will cause the air ride to vent. When the vehicle is lowered the rear of the vehicle will be in the fully lowered position.

May 08, 2011 | 2000 Mercury Grand Marquis

1 Answer

1999 Towncar - Air suspension shocks in good condition and car rides level - no idicator light is on. The car just rides way too stiff. Even the slightest bump jolts the inside (rattles change in ash...


I will check the shop manual, but the module does control ride for stiffness, increased stiffness at higher speeds, etc. If the bags are inflated, then the module cintrols how much air to allow in or out based on inputs to the module. See if you can get one from a salvage yard form a cash for clunkers car.

A dealer can run a test for fault codes in the computer. Call and ask how much for just a scan for fault codes in the air suspension module.

-----------------------------
Vehicle Dynamic Suspension The vehicle dynamic suspension consists of the following components:
  • Rear air suspension control (RAS) module (5A919)
  • Snorkel
  • Drier
  • Air compressor (5319)
  • Air suspension switch (5K761)
  • Solenoid valve (5311)
  • Air spring (5560)
  • Air suspension height sensor (5359)
  • Air line
----------------------------------------------------------------------------
Rear Air Suspension Control Module
A microprocessor controls the air suspension system. The microprocessor and its supporting hardware are contained in the rear air suspension control module. The rear air suspension control module responds to signals from various sensors in the vehicle to maintain the programmed ride height while the vehicle is either moving or stopped. The rear air suspension control module accomplishes this by opening and closing solenoid valves to control the amount of air in the air spring(s). The rear air suspension control module turns on the compressor by applying voltage through the compressor relay to inflate the air spring(s) and raise the vehicle. The rear air suspension control module opens the vent solenoid to lower the vehicle by releasing air from the air spring(s) in response to signal inputs from the air suspension height sensor(s).
Air Suspension Switch
sxg~us~en~file=ani_caut.gif~gen~ref.gif CAUTION: The air suspension switch must be turned to the OFF position when the vehicle is hoisted, jacked, towed, jump started, or raised off the ground, to avoid unnecessary operation of the system and possible damage to the air suspension system components.
The air suspension switch provides a signal to the rear air suspension control module in the ON position to activate the system to maintain the programmed vehicle height.
Air Compressor
NOTE: The compressor contains a thermal overload circuit breaker. The circuit breaker automatically resets after a cool down period and after being tripped by excessive compressor motor heat.
The air compressor assembly consists of the compressor pump, electric motor and vent solenoid (must be installed as an assembly).
Air Suspension Height Sensor
The air suspension height sensor sends signals to the air suspension control module. There are three possible conditions that the air suspension control module interprets from the signals of the air suspension height sensors. The conditions are trim height, below trim height, or above trim height.
Solenoid Valve, Air Spring
sxg~us~en~file=ani_caut.gif~gen~ref.gif WARNING: Never rotate an air spring solenoid valve to the release slot in the air spring end cap fitting until all pressurized air has escaped from the air spring to prevent vehicle damage or personal injury.
The air spring solenoid valve allows air to enter and exit the rear air springs during height adjustment operations. The air spring solenoid valve is electrically operated and controlled by the air suspension control module.
Steering Sensor
The steering sensor provides the steering rate and position to the air suspension control module to avoid overcompensation of the air suspension during turns.
Inspection and Verification
  1. Verify the customer concern.
  1. NOTE: If the door ajar indicator is illuminated, repair the door ajar indicator. For additional information, refer to Section 413-09 .
    Visually inspect for obvious signs of mechanical and electrical damage.


Visual Inspection Chart Mechanical Electrical
  • Restricted suspension movement
  • Excessive vehicle load
  • Cut, severed or crimped air line(s)
  • Incorrectly mounted, damaged or disconnected height sensor
  • Damaged air spring(s)
  • Central junction box (CJB) Fuse:
    • 8 (10A)
    • 17 (10A)
  • Battery junction box (BJB) Fuse 12 (30A)
  • Loose or corroded connectors
  • Air suspension switch
  • Damaged air spring solenoid(s)


  1. If the concern remains after the inspection, connect New Generation STAR (NGS) Tester to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the NGS Tester menu. If NGS Tester does not communicate with the vehicle:
    • check that the program card is properly installed.
    • check the connections to the vehicle.
    • check the ignition switch position.
  1. If the NGS still does not communicate with the vehicle, refer to the New Generation STAR Tester manual.
  1. Carry out the DATA LINK DIAGNOSTIC TEST. If NGS Tester responds with:
    • CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP. Refer to Section 418-00 .
    • NO RESP/NOT EQUIP for rear air suspension control module, go to Pinpoint Test A.
    • SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and perform self-test diagnostics for the rear air suspension control module.
  1. If the DTCs retrieved are related to the concern, go to Rear Air Suspension Control Module Diagnostic Trouble Code (DTC) Index to continue diagnostics.
  1. If no DTCs related to the concern are retrieved, proceed to Symptom Chart to continue diagnostics.
Rear Air Suspension Control Module Diagnostic Trouble Code (DTC) Index
NOTE: If rear air suspension control module C251 is disconnected before rear air suspension control module C250, DTCs C1830, C1770, C1790 and C1795 will be retrieved and must be cleared before an accurate list of continuous DTCs can be retrieved. The DTCs C1441 and C1442 will only be retrieved when running the electronic variable orifice (EVO) functional test on NGS Tester. The DTC C1897 will only be retrieved once per ignition switch cycle.

-----------------------------------------------------------------------------------
Module —Air Suspension Control Removal
sxg~us~en~file=ani_caut.gif~gen~ref.gif WARNING: Before performing maintenance on any air suspension components, disconnect the power to the system by turning off the air suspension switch located on the LH side of the luggage compartment to prevent vehicle damage or personal injury.
sxg~us~en~file=ani_caut.gif~gen~ref.gif CAUTION: Electronic modules are sensitive to static electrical charges. If exposed to these charges, damage may result.
  1. Turn the air suspension switch off.
  1. Disconnect the battery ground cable (14301).
  1. Pull out the lower instrument panel insulator.
    1. Remove the pushpins.
    1. Pull out the lower instrument panel insulator.
  1. Remove the lower instrument panel insulator.
    1. Disconnect the power point.
    1. Disconnect the courtesy lamp.
    1. Remove the lower instrument panel insulator.
  1. Remove the rear air suspension control module.
    1. Remove the screws.
    1. Disconnect the electrical connectors.
    1. Remove the rear air suspension control module.
Installation
  1. NOTE: When the battery is disconnected and reconnected, some abnormal drive symptoms may occur while the vehicle relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 mi) or more to relearn the strategy.
    To install, reverse the removal procedure.

Jan 20, 2010 | Lincoln Town Car Cars & Trucks

1 Answer

Hummer H2 SUT DTC Code C0563


u need to change/service the air compressor in ur car.
or it might be the air bags/sensors thats located next to the rear tires.

May 29, 2009 | 2005 Hummer H2

5 Answers

Air Suspension for 2004 Hummer H2


hummer h2 hydraulic keeps running depleting battery.

May 22, 2009 | 2004 Hummer H2

2 Answers

Airride suspension won't deflate only inflate


It will only process a "down command" if it thinks all the doors are closed. If you have a bad door switch, it won't lower. Any courtesy lights on with doors closed?
The dealer can conduct a diagnostic scan test and retrieve any codes that will help identify the bad circuit. Did they do that?

Do you have 4 wheel air suspension or just rear?

Assuming rear only:
The system consists of unique rear air springs, the air compressor, air lines, air spring solenoids, height sensor, air suspension control module, attachments and associated signals derived from both driver and road inputs. With these components and signals, the air suspension control module commands changes in vehicle height that are necessary for the load leveling features.
The load leveling feature rear air suspension (RAS) systems shall automatically make adjustments in vehicle height so that the vehicle is always at trim height and constant front-to-rear vehicle attitudes are maintained over the expected load range of the vehicle. Adjustments in height that are necessary to correct height differences between the vehicle's left and right sides for the RAS system shall be restricted to what can be reliably achieved with one air suspension height sensor.
The system uses one air suspension height sensor, a steering sensor, generic electronic module (GEM) and other vehicle sensors to measure driver and road inputs. The system changes vehicle height using an air compressor, two air lines and the use of air springs with air spring solenoids.

Note this section.
The air suspension system holds vehicle height when the rear hatch or any door is opened. The system stores rear vehicle height the moment any open door is detected. The system then maintains this height regardless of the addition or removal of a load. The system will return to its commanded height when all doors are closed or the vehicle speed exceeds 16 km/h (10 mph).

Air Suspension Switch
The air suspension switch supplies power to the air suspension control module. Without the air suspension control module receiving this power, the load leveling system is inoperative and will not react when the rear of the vehicle is raised or lowered. If the air suspension system is disabled by turning off the air suspension switch, a "CHECK SUSP" will appear in the RH corner of the instrument cluster with the ignition in the run position.
--------------------------------------------------------------------
The vent solenoid:
  • allows air to escape from the system during venting actions.
  • is part of the air compressor cylinder head.
  • has a 1,103 kPa (160 psi) internal relief valve.
  • shares a common electrical connector with the air compressor motor.
  • is enclosed in the cylinder head casting, which forms an integral valve housing that allows the valve tip to enter the pressurized side of the system.
  • has an O-ring seal that prevents air leakage past the valve tip.
  • opens when the air suspension control module determines lowering is required.
  • provides an escape route for pressurized air that opens when system pressures exceed safe operating levels.
  • is replaced with the air compressor as a unit.
---------------------------------------------------------------
Air Suspension Height Sensor
One air suspension height sensor is mounted on the vehicle. The air suspension height sensor sends a voltage signal to the air suspension control module. The output ranges from approximately 4.75 volts at minimum height (when the vehicle is low or in full jounce), to 0.25 volts at maximum height (when the vehicle is high or in full rebound). The air suspension height sensor has a useable range of 80 mm (3.2 in) compared to total suspension travel of 200-250 mm (8 to 10 in) at the wheel. Therefore, the air suspension height sensor is mounted to the suspension at a point where full rear suspension travel at the wheel is relative to 80 mm (3.2 in) of travel at the air suspension height sensor. The air suspension height sensor is attached between the No. 5 frame crossmember (upper socket) and the panhard rod (lower socket).
When the air suspension height sensor indicates that the rear of the vehicle is lower than trim under normal driving conditions, the air compressor will turn on and pump compressed air to the air springs. When the sensor indicates that the rear of the vehicle is raised above trim under normal driving conditions, this will cause the air to be vented from the air springs to lower the vehicle back to its trim height level.
Compressor Relay
The compressor relay is energized by the air suspension control module to allow high current to flow from the battery to the compressor motor.
  • A solid state relay is used in the air suspension system for air compressor control. The relay incorporates a custom power metal oxide semi-conductor field effect transistor (MOSFET) and ceramic hybrid circuitry. The relay switches high current loads in response to low power signals and is controlled by the logic of the air suspension control module.
Air Suspension Control Module
NOTE: The 4WAS air suspension control module is used for the RAS system. The internal processor recognizes external circuitry to determine if it is installed in a 4WAS or a RAS equipped vehicle.
NOTE: The air suspension control module is calibrated with information from the air suspension height sensor. A new or exchanged air suspension control module requires a ride height adjustment calibration process to be performed.
The air suspension control module controls the air compressor motor (through a solid state relay), and the air spring solenoids. The air suspension control module also provides power to the air suspension height sensor. The air suspension control module controls vehicle height adjustments by monitoring the air suspension height sensor, vehicle speed, a steering sensor, acceleration input, the door ajar signal, transfer case signals, and the brake pedal position (BPP) switch. The air suspension control module also conducts all fail-safe and diagnostic strategies and contains self-test and communication software for testing the vehicle and related components.
The air suspension control module monitors and controls the air suspension system through a 32-pin two-way connector. The air suspension control module is keyed so that the air suspension control module cannot be plugged into an incorrect harness. There are two sides of the harness connection to the air suspension control module. Each is uniquely colored and keyed to prevent reversing the connections.
---------------------------------------------------
May be a bad module too.

Apr 11, 2009 | 2000 Lincoln Navigator

1 Answer

Driver side air bag suspension will not stay inflated on my 94


Check the sensor located on the rear A-arm, I think it is what send the signal to the compressor telling it to raise or lower the suspension.

Mar 14, 2009 | 1994 Lincoln Continental

1 Answer

I need to know how to get to the rear suspension (tower)


i don't think you have to do any repairs from the top end. I will list most fromFord shop manual. Please rate as Fixya if this answers your questions. Please report back. Good luck.

Section 04-02: Suspension and Wheel Hubs, Rear 1994 Town Car, Crown Victoria/Grand Marquis. Workshop Manual
REMOVAL AND INSTALLATION Spring Rear
Removal
  1. Position a hoist under the rear axle housing, and raise the vehicle. Refer to Section 00-02 . Place jackstands under frame side rails.
  1. Remove rear stabilizer bar as outlined.
  1. Disconnect the lower studs of the two shock absorbers from the mounting brackets on the rear axle assembly .
  1. Unsnap the RH parking brake rear cable and conduit (2A635) from RH upper arm retainer before lowering the rear axle assembly .
  1. Lower the hoist and axle housing until the rear springs are released.
  1. Remove rear spring and rear spring center mounting insulators (5741) from vehicle.
    -----------------------------------------------------------------
Shock Absorber Removal
Raise the vehicle on a hoist. 1. To assist in removing the upper attachment on shock absorbers using a plastic dust tube, place an open end wrench on the hex stamped into the dust tube's metal cap. For shock absorbers with a steel dust tube, simply grasp the tube to prevent stud rotation when loosening the retaining nut.
  1. Remove the shock absorber retaining nut, washer, and insulator assembly from the stud on the upper side of the frame. Discard nut. Compress the shock absorber to clear the hole in the frame, and remove the inner insulator and washer from the upper retaining stud.
  2. Remove the self-locking retaining nut, and disconnect the shock absorber lower stud from the mounting bracket on the rear axle tube.
  3. Perform Shock Absorber Checks. Refer to Section 04-00 to determine shock absorbers performance.
Installation
  1. Properly prime the new shock absorber . Refer to Section 04-00 , Shock Absorber Checks.
  1. Place the inner washer and rear spring insulator (5536) on the upper retaining stud, and position the shock absorber so that the upper retaining stud enters the hole in the frame. While holding the shock absorber in this position, install a new rear spring insulator , washer and nut assembly on the upper side of the upper frame. Be sure to seat the rear spring insulator in the frame attaching hole. Tighten nut to 34-46 Nm (25-34 lb-ft).
  1. Extend the shock absorber , and place the lower stud in the mounting bracket hole on the rear axle assembly housing. Install a new self-locking retaining nut. Tighten nut to 76.5-103.5 Nm (56-76 lb-ft).
  1. Lower vehicle.
-----------------------------------------------------------------------------
Arm Lower
Removal
Refer to the illustration in Description and Operation. NOTE: To improve rear axle assembly noise and vibration concerns, the rear suspension should be fastened to the frame and rear axle assembly at the curb height position.
NOTE: If one rear suspension lower arm requires replacement, also replace the opposite rear suspension lower arm .
sra~us~en~file=ani_caut.gif~gen~ref.gif WARNING: TURN REAR SUSPENSION LEVELER COMPRESSOR SWITCH OFF (IF SO EQUIPPED).
NOTE: If both rear suspension arm and bushings and both rear suspension lower arms are to be removed at the same time, remove both rear springs as outlined under Rear Spring Removal. For air spring removal, refer to Section 04-05 .
  1. Mark rear suspension shock absorber relative to protective sleeve with the vehicle in a static, level ground condition.
  1. Remove rear stabilizer bar as outlined.
  1. Raise the vehicle on a hoist, and place jackstands under the rear axle assembly . Refer to Section 00-02 .
  1. Lower the hoist until the shock absorbers are fully extended to relieve rear spring pressure.
  1. Support rear axle assembly under differential pinion nose as well as under rear axle assembly .
  1. Remove and discard the lower arm pivot bolt and nut from the axle bracket. Then, disengage the rear suspension lower arm from the bracket.
  1. Remove and discard the pivot bolt and nut from the frame bracket, and remove the rear suspension lower arm .
-----------------------------------------------------------------
Upper
Removal
SPECIAL SERVICE TOOL(S) REQUIRED Description Tool Number Suspension Bushing Service Set T79P-5638-A1, A2 and A5 Rear Axle Control Arm Bushing Tools T86P-5638-AH
sra~us~en~file=ani_caut.gif~gen~ref.gif WARNING: TURN OFF REAR SUSPENSION LEVELER COMPRESSOR SWITCH (IF SO EQUIPPED).
  1. Raise the vehicle, and support the frame side rails with jackstands. Refer to Section 00-02 .
  2. Support the rear axle assembly .
  3. Lower the rear axle assembly , and support the rear axle assembly under differential pinion nose as well as under rear axle assembly .
  4. Unsnap parking brake rear cable and conduit from upper arm retainer.
  5. Remove and discard the nut and bolt retaining the rear suspension arm and bushing to the rear axle assembly housing. Disconnect the rear suspension arm and bushing from the housing.
  6. Remove and discard the nut and bolt that secures the rear suspension arm and bushing to the frame bracket, and remove the rear suspension arm and bushing . If upper arm rear bushing is to be replaced, use Suspension Bushing Service Set T79P-5638-A and Rear Axle Control Arm Bushing Tools T86P-5638-AH and the following procedure:
  7. Place the upper arm rear bushing remover tool in position, and pull bushing out. Using Suspension Bushing Service Set T79P-5638-A install bushing assembly into bushing ear of rear axle assembly.
------------------------------------------------
Stabilizer Bar
sra~us~en~file=ani_caut.gif~gen~ref.gif WARNING: TURN OFF REAR SUSPENSION LEVELER COMPRESSOR SWITCH (IF SO EQUIPPED).
Removal
  1. Raise vehicle on hoist, and place jackstands under the frame side rails. Refer to Section 00-02 .
  1. Lower the hoist and rear axle assembly housing until the shock absorbers are fully extended.
  1. Disconnect rear stabilizer bars from rear stabilizer bar link and bushing (5C488) . Remove bolts and stabilizer bar bracket (5486) retaining rear stabilizer bar to rear axle assembly .

Mar 05, 2009 | 1994 Lincoln Town Car

2 Answers

AIR SUSPENTION WORKS ABNORMALY


a lot of info here:
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).


Vehicle Height Modes Ignition State Transfer Case Mode Speed or Speed Range Resulting Vehicle Height OFF 4x2, A4WD, 4x4 HI N/A Kneel (TRIM - 25 mm) ON and RUN 4x2, A4WD, 4x4 HI All speeds TRIM ON and RUN 4x4 Low Below 40 km/h (25 mph) Off-Road (TRIM + 25 mm) ON and RUN 4x4 Low Above 40 km/h (25 mph) TRIM OFF 4x4 Low N/A Stays at current position (prior to ignition transition)
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"
Air Compressor
The air compressor:
  • consists of the compressor and vent solenoid; neither are replaceable as individual items.
  • is a single cylinder electric motor driven unit that provides pressurized air as required.
  • is powered by a solid state relay, which is controlled by the 4WAS module.
  • passes pressurized air through the compressor air drier that contains silica gel (a drying agent). Moisture is then removed from the compressor air drier when vented air passes out of the system during vent operation.
  • has a single port drier that can be replaced separately.
The vent solenoid:
  • allows air to escape from the system during venting actions.
  • is part of the air compressor cylinder head.
  • shares a common electrical connector with the air compressor motor.
  • is enclosed in the cylinder head casting, which forms an integral valve housing that allows the valve tip to enter the pressurized side of the system.
  • has an O-ring seal that prevents air leakage past the valve tip.
  • opens when the 4WAS module determines that lowering is required.
  • provides an escape route for pressurized air when system pressures exceed safe operating levels.
  • has a 1034 kPa (150 psi) internal relief valve.
  • is installed with the air compressor as a unit.
Air Spring
The 4WAS system has front and rear air springs. The air springs provide a varying spring rate proportional to the system's air pressure and volume. The air suspension system regulates the air pressure in each air spring by compressing and venting the system's air. Increasing air pressure (compressing) raises the vehicle; decreasing air pressure (venting) lowers the vehicle. Vehicle height is maintained by the addition and removal of air in each air spring through an air spring solenoid installed in the upper spring cap and energized through the 4WAS module command.
Air Lines and Fittings
NOTE: Apply a soapy water solution to the air lines to verify the location of air leaks. If the air lines are cut, ruptured or leaking, a service repair kit is available.
Nylon air lines with quick connect fittings connect to the air compressor and air spring solenoids. The compressor assembly output line is divided by the use of a fitting to supply the front and rear air springs. Fittings are also used to divide the air supply to the RH and LH air spring solenoids.
Air Suspension Height Sensors
There are two sensors used for the front suspension and one sensor used for the rear suspension. The sensors send a voltage signal to the 4WAS module. The output ranges from approximately 4.50 volts at minimum height (when the vehicle is low or in full jounce) to 0.50 volt at maximum height (when the vehicle is high or in full rebound). The sensors have a usable range of ± 45° compared to total suspension travel of 196 mm (7.84 in) at the front wheels and 240 mm (9.6 in) at the rear wheels. Therefore, the sensors are mounted to the suspension at a point where full suspension travel at the wheel is relative to the travel at the height sensor. The front height sensors are mounted to the frame and the links are attached to the upper arm ball studs. The rear height sensor is mounted to the frame and the link is attached to the rear lower arm ball stud.
When the height sensor indicates that the vehicle is lower than trim under normal driving conditions, the air compressor will turn on and pump compressed air to the system. When the sensor indicates that the vehicle is raised above trim under normal driving conditions, this will cause the air to be vented from the system to lower the vehicle to its trim height level.
Compressor Relay
A solid state relay is used in the air suspension system for compressor control. The relay incorporates a custom power metal oxide semi-conductor field effect transistor (MOSFET) and ceramic hybrid circuitry. The relay switches high current loads in response to low power signals and is controlled by the logic of the 4WAS module.
The compressor solid state relay is energized by the 4WAS module to have high current flow from the battery to the compressor motor.
4-Wheel Air Suspension (4WAS) Module
NOTE: The 4WAS module must receive a ride height adjustment calibration and must pass a pneumatic test when it is installed new or swapped.
The 4-wheel air suspension (4WAS) module controls the air compressor motor (through a solid state relay), all air spring solenoids, and provides power to front and rear height sensors. The 4WAS module also controls vehicle height adjustments by monitoring the three height sensors and other universal bus protocol (UBP) signals. The 4WAS module conducts all fail-safe and diagnostic strategies, and contains self-test and communication software for testing the vehicle and related components.

Jan 06, 2009 | 2003 Lincoln Navigator

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