Question about 1997 Cadillac Seville

2 Answers

Air ride out of control on 97 STS

The air shocks are fully extended and pressurized. I replaced the ride height control module at each of the rear wheels but it made no difference. Adding weight (500Lbs) to the trunk made no difference. The car did not go down nor did the weight cause the air pump to run.

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  • dickschulz Jul 10, 2010

    The air shocks remain pressurized (I believe fully extended) for a week long period and for this reason I don't think they leak, unless the pump runs automatically without the ignition turned on. The mention of water intrusion may bear some invwstigation. The sun roof may allow a water leak into the trunk. I discovered about 2 inches of water in the spare tire well about the same time I felt the harsh ride from the extended shocks.

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  • Cadillac Master
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Hello! The Electronic Level Control is not allowing air to escape as weight increases...It is the Compressor plus the exhaust solenoid...It is powered by the ELC maxi-fuse (30A) In the maxi-fuse block...Try the fuse first...If it is OK...More than likely the exhaust solenoid (relay) is bad...It's a common relay and Cost around $12...Guru.............Saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

Posted on Jul 11, 2010

  • dickschulz Jul 11, 2010

    Where can I physically locate this relay on the vehicle?

  • David Burbee
    David Burbee Jul 11, 2010

    Hello! The Electronic Leveling Compressor is located underneath the car...Near the right rear wheel...Follow the plastic tubing from the shock to pinpoint location...A connector with wire colors...Orange and White...Is the Exhaust Solenoid...The vent, which allows air to escape may also be plugged...This vent is opened mechanically when the Exhaust Solenoid is pulled...

    Let me know what you find................saailer


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  • Master
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A leak seems the most likely suspect, but a visual inspection doesn't detect one. Pull the relay and then check the control circuit (LED test
light)... if the LED does not light-up, replace the SAI relay.
The other possible reasons for air pump not running are Blown air pump fuse,Blown/shorted Air pump motor, The air pump filter clogged or loose. The secondary air solenoid leaking vacuum causing air pump valve to open at incorrect time (possibly from water intrusion); replace solenoid. Check out.Thanks.

Posted on Jul 10, 2010

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1 Answer

My 2005 Lincoln navigator has a new compressor and it lifts up but I must restart it to get it to lift. could you please tell me why


Have to restart what ? Vehicle ? Did you have the system check for code's ?
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
  • Compressor relay
  • Vehicle Dynamic Module (VDM) Diagnostic Trouble Code (DTC) Index NOTE: Repair all other DTCs before C1725 and C1726. Repair DTCs C1990 and C1991 last. DTCs Description Source Action B1317 Battery voltage high VDM Go To Pinpoint Test C . B1318 Battery voltage low VDM Go To Pinpoint Test C . B1342 ECU is defective VDM INSTALL a new VDM. REFER to Air Suspension Control Module in this section. SET the ride height. REFER to Ride Height Adjustments in this section. CARRY OUT the pneumatic test. TEST the system for normal operation. B2477 VAPS II steering assist curve not complete VDM REFER to Section 211-00 . C1445 Vehicle speed signal circuit failure VDM GO to Symptom Chart . C1724 Air suspension height sensor power circuit failure VDM Go To Pinpoint Test D . C1725 Air suspension front pneumatic failure VDM Go To Pinpoint Test E . C1726 Air suspension rear pneumatic failure VDM Go To Pinpoint Test E . C1760 Air suspension rear height sensor signal circuit failure VDM Go To Pinpoint Test F . C1770 Air suspension vent solenoid output circuit failure VDM Go To Pinpoint Test G . C1790 Air suspension LR air spring/shock solenoid output circuit failure VDM Go To Pinpoint Test H . C1795 Air suspension RR air spring/shock solenoid output circuit failure VDM Go To Pinpoint Test H . C1830 Air suspension compressor relay circuit failure VDM Go To Pinpoint Test I . C1840 Air suspension disable switch circuit failure VDM Go To Pinpoint Test J . C1873 Air suspension RF air spring solenoid output circuit failure VDM Go To Pinpoint Test H . C1877 Air suspension LF air spring solenoid output circuit failure VDM Go To Pinpoint Test H . C1881 Air suspension RF height sensor circuit failure VDM Go To Pinpoint Test F . C1889 Air suspension LF height sensor circuit failure VDM Go To Pinpoint Test F . C1897 Steering VAPS circuit loop failure VDM REFER to Section 211-00 . C1964 Air suspension compressor actual run time exceeded allowed run time VDM Allow the air compressor to cool down. CLEAR the DTC. REPEAT the self-test. C1990 New control module initialization (requires ride height calibration and pneumatic test pass) VDM REFER to "Clearing DTC C1990 or C1991". C1991 Plant ride height setting and/or tests incomplete VDM REFER to "Clearing DTC C1990 or C1991".

May 23, 2018 | Lincoln Cars & Trucks

1 Answer

06 cad STS. Loud pitch noise coming from trunk area. Not the parking assist. Does it while driving. Only ways to make it stop is to cut off car. Sometimes comes right back on when start car back up


Air compressor for load leveling system ?

Automatic Level Control (ALC) Compressor
(2) Automatic Level Control (ALC) Exhaust Solenoid

The Automatic Level Control (ALC) system automatically adjusts the rear height of the vehicle in response to changes in vehicle loading.
The ALC system consists of the Electronic Suspension Control module, 2 position sensors, an air compressor assembly, an ALC compressor relay, an intake hose and filter, an air tube, and 2 rear shock absorbers. The air compressor assembly consists of an air compressor and an air dryer mounted on a bracket. The air compressor head is a replaceable part of the air compressor. The exhaust solenoid is a non-replaceable part of the air compressor head.
The vehicles rear vertical height is measured by the 2 position sensors. These 2 position sensors convert this rear height measurement into an analog voltage which is read by the ESC module. The ESC module then determines what action exhaust, compress, or no action shall take place. To compress, the ESC module switches the ELC compressor relay to ground.
The compressor is activated when the ignition is on, and weight is added to the vehicle. The exhaust solenoid is connected directly to the battery (+), enabling the system to exhaust with the ignition on or off when excess weight is removed.

Feb 07, 2017 | 2006 Cadillac STS

1 Answer

2007 Yukon Denali XL autoride suspension light comes on intermittently


Would need to know what DTC'S - diagnostic trouble codes are stored in the module for the autoride suspension . Hooking up a professional type scan tool ,looking at input data to the module etc... Looking at a wiring diagram an testing electrical circuit's using a DMM - digital multi-meter . Reading how the system works ,what all involved in making the system work . This is how a professional Tech would go about diagnosing this .

The automatic level control (ALC) system maintains a desired rear suspension position under all types of towing, hauling and loading conditions. The following components are involved in the operation of the ALC system:
• Air line tubing--Pressurized air from the ALC compressor is pumped to each of the rear shocks via air line tubing.
• Air drier--Pressurized air from the compressor is run through a drier containing a moisture absorbing chemical preventing water accumulation in the rear shocks.
• Compressor--Supplies pressurized air to the rear shocks
• Compressor motor relay--The relay supplies battery positive voltage to the ALC compressor motor.
• Pressure sensor--The electronic suspension control module (ESCM) module provides a 5-volt reference and low reference to the ALC pressure sensor. The module receives the signal voltage that is relative to the air pressure applied to the rear shocks.
• ESCM--Controls the ALC system and electronic suspension control (ESC) system and detects failures in both. The module monitors inputs from the position sensors, and pressure sensor to determine when to raise and lower the vehicle to trim height as the vehicle is loaded or unloaded. The module limits pump activation to 255 seconds to prevent thermal damage.
• Exhaust valve--An electric solenoid activated by the ESCM to vent air pressure from the rear shocks.
• Left and right rear suspension position sensors--The module provides a 5-volt reference and low reference to all 4 of the body-to-wheel suspension position sensors. The sensors send the ESCM a signal voltage that is relative to the rear suspension ride height
• Left and right rear shock absorbers with internal air chambers and dampers--Dampens the rear suspension and maintains trim height depending on the air pressure applied.

Nov 04, 2017 | 2007 GMC Yukon XL Denali

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

I have a 1994 lincoln continental car. Hoe do I replace the suspention drier?


why do you want to replace it? As air is exhausted through it, it dires it out for the next use. it's part of compressor assembly.

1996 cont'l The air suspension system includes the following major components:
  • Air compressor to supply air to the air springs (part of front spring and shock and rear spring and shock absorber assemblies
  • Front spring and shock (3C098) and rear spring and shock absorber (5A965) at each corner of the vehicle
  • Four linear air suspension height sensors (5359): two rear and two front height sensors to maintain the vehicle at the proper ride height; only LH rear height sensor is used for air suspension.
  • Dual-mode front spring and shock and rear shock absorber assemblies with internal actuator.
All system functions are controlled by vehicle dynamics control module (5A919). This control module receives inputs from several different sources. These inputs include:
  • vehicle speed via multiplex communication network
  • ignition switch position
  • door position via multiplex communication network
  • height sensor position
  • air suspension service switch
  • engine rpm via multiplex communication network
  • ride and steering personality settings via multiplex communications network
Communications monitor system operation and allow diagnosis of any concerns that may develop in the system. System monitoring for the driver's use is provided through the instrument panel mounted message center indicator (10D898).
  • Diagnosis communication for the service technician is provided through the data link connector (14489) (DLC) under the instrument panel and Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent.
The message center indicator will display AIR LEVELING DISABLED or CHECK RIDE CONTROL if the suspension system is not turned on or the vehicle dynamics control module detects a concern. If air leveling system disabled is displayed, check that air suspension service switch is in the ON position.
----------------------------------------------------------
Solenoid Valve Vent The vent solenoid valve operates as follows:
  • The vent solenoid valve allows air to escape from the system during venting corrections.
  • The valve is located in the air compressor cylinder head and shares a common electrical connector with the motor.
  • The valve 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.
  • Air leakage past the valve tip is prevented by an O-ring seal.
  • The vent solenoid valve opens when a corner of the vehicle is high and the vehicle dynamics control module (5A919) determines lowering is required.
  • When the vent solenoid valve is opened, it provides an escape route for pressurized air.
  • However, the vehicle will not lower unless the air spring solenoid valves (5311) are also opened to allow air to leave the springs.
  • Lowering the vehicle corners requires the vehicle dynamics control module to open two solenoid valves, the vent and one air spring solenoid.
  • Air is exhausted from the spring and vents through the compressor air drier (5346).
---------------------------------------------------------------------------------------------
Section 04-05: Suspension, Computer Controlled 1996 Continental Workshop Manual
REMOVAL AND INSTALLATION Air Compressor and Drier Assembly Removal
  1. Turn air suspension service switch OFF.
  1. Disconnect electrical connector located on the air compressor.
  1. Disconnect two air lines from compressor air drier.
  1. Remove three fasteners retaining air compressor and drier assembly to radiator support, frame rail and fender apron.

Dec 22, 2009 | 1994 Lincoln Continental

3 Answers

The rear suspension air bags no work


start here

The air suspension system is designed to improve ride, handling and general vehicle performance for static, on-road and off-road driving condition:
  • Ride is improved by using an air type spring (the soft ride is inherent).
  • Handling is improved by maintaining constant vehicle attitude.
The system consists of unique rear air springs, 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 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) transfer case inputs, 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 an air spring with an air spring solenoid.
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 and the vehicle speed exceeds 16 km/h (10 mph).
Air Suspension Switch
The air suspension switch is located behind the RH kick panel on a mounting bracket. The switch interrupts power to the air suspension control module.
The air suspension switch supplies a signal to the air suspension control module. Without the air suspension control module receiving this signal the load leveling system is inoperative and will not react when rear of the vehicle is raised or lowered. If the air suspension system is disabled by turning off air suspension switch, a "CHECK SUSP" will appear in the RH corner of the instrument cluster with the ignition in the run position.
Air Compressor
The RAS air compressor:
  • Is not interchangeable with four wheel air suspension (4WAS) compressor.
  • Consists of the compressor and vent solenoid; neither are replaceable as individual items.
  • Is mounted in the engine compartment between the washer fluid bottle and headlamp (RH front corner).
  • Is a single cylinder electric motor driven unit that provides pressurized air as required.
  • Is powered by a solid state relay, controlled by the air suspension control 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.
  • Air drier has a single port and is not interchangeable with 4WAS compressor air drier.
  • Air drier may be replaced separately.
  • Incorporates a snorkle that may be replaced separately.
The vent solenoid:
  • Allows air to escape from the system during venting actions.
  • Is located in the air compressor cylinder head.
  • Has a 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 Spring
RAS vehicles use air springs in the rear. The air springs provide a varying spring rate proportional to the systems air pressure and volume. The air suspension system regulates the air pressure in each air spring by compressing and venting the system air. Increasing air pressure (compressing) raises the rear of the vehicle while decreasing air pressure (venting) lowers the rear of 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 air suspension control module.
The air springs are mounted between the axle spring seats and the frame upper spring seats.
The two air springs replace the conventional rear coil springs.
Air Suspension Height Sensor
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.
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 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 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). Replace the air suspension height sensor as a unit.
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 of the vehicle and related components.
The air suspension control module is mounted in the passenger compartment inside the instrument panel above the radio and temperature controls.
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.
Air Suspension Diagnostic Connector
The air suspension diagnostic connector is used to aid the technician in diagnosing the air suspension system. It is also used to vent the system of compressed air when air suspension system components need to be repaired or replaced. The air suspension diagnostic connector is located under steering column.

Oct 02, 2009 | 1998 Ford Expedition

3 Answers

Rear air bag suspension failure 1998 Ford EXP E.B. 2x2


this will get you started. report back on progress and we'll go from there. There is a diagnostic test that will provide codes I think. I will look.

The system consists of unique rear air springs, 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 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) transfer case inputs, 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 an air spring with an air spring solenoid.
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 and the vehicle speed exceeds 16 km/h (10 mph).
Air Suspension Switch
The air suspension switch is located behind the RH kick panel on a mounting bracket. The switch interrupts power to the air suspension control module.
The air suspension switch supplies a signal to the air suspension control module. Without the air suspension control module receiving this signal the load leveling system is inoperative and will not react when rear of the vehicle is raised or lowered. If the air suspension system is disabled by turning off air suspension switch, a "CHECK SUSP" will appear in the RH corner of the instrument cluster with the ignition in the run position.
Air Compressor
The RAS air compressor:
  • Is not interchangeable with four wheel air suspension (4WAS) compressor.
  • Consists of the compressor and vent solenoid; neither are replaceable as individual items.
  • Is mounted in the engine compartment between the washer fluid bottle and headlamp (RH front corner).
  • Is a single cylinder electric motor driven unit that provides pressurized air as required.
  • Is powered by a solid state relay, controlled by the air suspension control 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.
  • Air drier has a single port and is not interchangeable with 4WAS compressor air drier.
  • Air drier may be replaced separately.
  • Incorporates a snorkle that may be replaced separately.
The vent solenoid:
  • Allows air to escape from the system during venting actions.
  • Is located in the air compressor cylinder head.
  • Has a 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 Spring
RAS vehicles use air springs in the rear. The air springs provide a varying spring rate proportional to the systems air pressure and volume. The air suspension system regulates the air pressure in each air spring by compressing and venting the system air. Increasing air pressure (compressing) raises the rear of the vehicle while decreasing air pressure (venting) lowers the rear of 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 air suspension control module.
The air springs are mounted between the axle spring seats and the frame upper spring seats.
The two air springs replace the conventional rear coil springs.
Air Suspension Height Sensor
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.
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 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 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). Replace the air suspension height sensor as a unit.
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 of the vehicle and related components.
The air suspension control module is mounted in the passenger compartment inside the instrument panel above the radio and temperature controls.
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.
Solenoid Valve, Air Spring
swj~us~en~file=ani_caut.gif~gen~ref.gif WARNING: Never rotate an air spring solenoid valve to the release slot in the end cap fitting until all pressurized air has escaped from the spring to prevent damage or injury.
The air spring solenoid:
  • allows air to enter and exit the air spring during leveling operations.
  • is electrically operated and controlled by the air suspension control module.
Air Suspension Diagnostic Connector
The air suspension diagnostic connector is used to aid the technician in diagnosing the air suspension system. It is also used to vent the system of compressed air when air suspension system components need to be repaired or replaced. The air suspension diagnostic connector is located under steering column.

Jun 01, 2009 | 1998 Ford Expedition

1 Answer

REPLACED DRYER ON 96 CONT NOW THE BACK WONT AIR UP FRONT DOES


maybe you got dirt in the line to the rear. Here's some background info:

The air suspension system includes the following major components:
  • Air compressor to supply air to the air springs (part of front spring and shock and rear spring and shock absorber assemblies
  • Front spring and shock (3C098) and rear spring and shock absorber (5A965) at each corner of the vehicle
  • Four linear air suspension height sensors (5359): two rear and two front height sensors to maintain the vehicle at the proper ride height; only LH rear height sensor is used for air suspension.
  • Dual-mode front spring and shock and rear shock absorber assemblies with internal actuator.
All system functions are controlled by vehicle dynamics control module (5A919). This control module receives inputs from several different sources. These inputs include:
  • vehicle speed via multiplex communication network
  • ignition switch position
  • door position via multiplex communication network
  • height sensor position
  • air suspension service switch
  • engine rpm via multiplex communication network
  • ride and steering personality settings via multiplex communications network
Communications monitor system operation and allow diagnosis of any concerns that may develop in the system.
  • System monitoring for the driver's use is provided through the instrument panel mounted message center indicator (10D898).
  • Diagnosis communication for the service technician is provided through the data link connector (14489) (DLC) under the instrument panel and Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent.
The message center indicator will display AIR LEVELING DISABLED or CHECK RIDE CONTROL if the suspension system is not turned on or the vehicle dynamics control module detects a concern. If air leveling system disabled is displayed, check that air suspension service switch is in the ON position.
-------------------------------------------------------
Weight Added When weight is added to the vehicle, the air suspension system responds as follows:
  • Air suspension height sensor length is reduced from trim length, sending a "vehicle is low" signal to the vehicle dynamics control module (5A919).
  • To restore vehicle to the trim position, the vehicle dynamics control module turns the compressor on by grounding the compressor relay control Circuit 420 (DB/Y). The relay is ground-side switched.
  • To allow pressurized air to enter the rear spring (5560) and front spring and shock (3C098), the control module opens the solenoid valves (5311).
  • Compressed air flows from the compressor, through the compressor air drier assembly, air lines and solenoid valves into the air springs.
  • As the air springs raise the body height, the air suspension height sensor (5359) increases in length until the preset trim height is reached.
  • The vehicle dynamics control module then turns off the compressor (through the relay) and closes the air spring solenoid valves.
  • ----------------------------------------------------------------------------
  • Weight Removed When weight is removed, the air suspension system responds as follows:
    • Air suspension height sensor length is increased from the trim length, sending a "vehicle is high" signal to the control module (5A919).
    • To restore the vehicle to the trim position, the vehicle dynamics control module opens the vent solenoid valve (located in the compressor assembly) and opens the solenoid valves (5311).
    • Compressed air flows from air springs, through the solenoid valves, air lines, compressor air drier (5346) and out the vent solenoid valve.
    • As the body lowers, the air suspension height sensor length decreases until the preset trim height is reached.
    • The vehicle dynamics control module then closes the vent and solenoid valves.
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Control Module Power and Ground The vehicle dynamics control module (5A919) is located above the upper luggage compartment trim panel and lower module tray. Module power is provided by Circuit 418 (DG/Y) at Pins 36, 37, 56, 57, 58 and is powered through a Fuse 7 (30A) in power distribution box. Module ground is provided through control module wire harness Pins 6, 39, 40 and 60. The data link connector (14489) (DLC) is located in the passenger compartment under the instrument panel, 300 mm (12 inches) right of the steering column. This connector allows communications between the vehicle dynamics control module and either Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent or Rotunda Service Bay Diagnostics System (SBDS)® 001-00001 or equivalent. When the CHECK RIDE CONTROL message is displayed in the message center indicator (10D898), a system error has been detected by the vehicle dynamics control module and is stored in the control module. This diagnostic trouble code (DTC) will be retained for the next 80 ignition switch cycles. If there is no repeat of the same error during these 80 ignition switch cycles, the control module will erase the DTC. Because of this self-erasing memory, a customer may have had a concern "just a few days ago" that is not retrieved from memory when Diagnostic Test Mode (DTC) "Retrieve/Clear Continuous DTCs" is executed. This must be kept in mind if you must tell customer that no current concern has been found. When the vehicle dynamics control module detects a concern, the air suspension system is disabled for the current ignition cycle. If the condition causing the concern clears up during the current ignition switch cycle, the system will not reactivate. For example, if the customer has severely overloaded the luggage compartment, the system will not be able to trim the vehicle without exceeding the compressor run time. This will generate a DTC that disables the computer controlled suspension system. If the customer then drives the vehicle and unloads the luggage compartment without turning the ignition switch OFF, the system will not adjust for the new load. The customer will experience poor ride quality and the vehicle will not adjust trim.

May 20, 2009 | 1996 Lincoln Continental

3 Answers

Rear air suspension compressor not engaging.


what year? here's 2003 rear air only info, not 4 wheel air.

you have a fuse panel in truck and 1 under hood.




Visual Inspection Chart Mechanical Electrical
  • Restricted suspension movement
  • Excessive vehicle load
  • Cut, severed or crimped air line(s)
  • Unmounted height sensor
  • Damaged air spring(s)
  • Open fuses:
    • Central junction box (CJB) Fuse 4 (15A), 6 (5A) and 20 (5A)
    • Battery junction box (BJB) Fuse 109 (50A)
  • Loose, corroded or disconnected connectors
  • Air suspension switch is in the OFF position
  • Damaged solenoid valve(s)

  • compressor is inoperative
  • BJB Fuse 109 (50A).
  • Air compressor assembly.
  • Circuitry.
  • Air suspension relay.
  • Go To Pinpoint Test P .



----------------------------------------------------------------------------

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.

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.
Air Compressor
The RAS 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 air suspension control 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.
  • air drier has a single port.
  • air drier may be replaced separately.
  • incorporates a snorkel that may be replaced separately.
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 Spring
RAS vehicles use air springs in the rear. The air springs provide a varying spring rate proportional to the systems air pressure and volume. The air suspension system regulates the air pressure in each air spring by compressing and venting the system air. Increasing air pressure (compressing) raises the rear of the vehicle while decreasing air pressure (venting) lowers the rear of 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 air suspension control module.
The two air springs support the conventional rear leaf coil springs.
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.
Solenoid Valve, Air Spring
s2j~us~en~file=ani_caut.gif~gen~ref.gif WARNING: Never rotate an air spring solenoid valve to the release slot in the end cap fitting until all pressurized air has escaped from the spring to prevent damage or injury.
The air spring solenoid:
  • allows air to enter and exit the air spring during leveling operations.
  • is electrically operated and controlled by the air suspension control module.
  • is only installed as a unit.

Apr 18, 2009 | 2003 Lincoln Navigator

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