Rear air suspension stuck at highest position

It's mostly electronic , There is a control module ,sensor's at the corners ,wheels , an electric compressor to pump air to raise the vehicle .
You don't say what make , model an year vehicle but there all pretty much the same . This is for a Cadillac Deville
The electronic suspension control (ESC) system consists of the following components:
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Electronic suspension control (ESC) module (3)

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Four dampers contained in the 2 front struts (5 and 6) and the 2 rear shock absorbers (1 and 9)

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Four positions sensors (2, 4, 7, and 8)

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ALC air compressor module (10)

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Damper relay (not shown)

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ELC relay (not shown)

The ESC system with rear automatic level control (ALC) controls damping forces in the front struts and rear shock absorbers in response to various road and driving conditions. The rear ALC portion of the system maintains a proper vehicle trim height under various vehicle load conditions. For more information on the ALC, refer to Automatic Level Control Description and Operation in Automatic Level Control.
The ESC module receives the following inputs: wheel-to-body position, vehicle speed, and lift/dive. The ESC module evaluates these inputs and controls actuators in each of the dampers independently to provide varied levels of suspension control.
Your best bet is take it to the dealer !

look for a little lever on rear suspension to electrical valve for shocks
it is not attach or missing to small ball
hope it helps

the buzzer may just be a reminder to make you look at the dash to see that warning light.
You may need to get the dealer to have a look at it.
Sorry that isn't a solution, but something is better than nothing.

Need a repair shop to diagnose the
air ride system
Can't guess form here,always need the
patient

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.

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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

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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
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
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.

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Module —Air Suspension Control Removal
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.
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.

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

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Visual Inspection Chart Mechanical Electrical

• Restricted suspension movement
• Excessive vehicle load
• Cut, severed, or crimped air line(s)
• Damaged air spring(s)
• Height sensor damage
• Height sensor mounted incorrectly, disconnected, or damaged

• Central junction box (CJB):
  • Fuse 5 (15A)
• Battery junction box (BJB):
  • Fuse 8 (30A)
• Loose or corroded connectors
• Air suspension switch OFF

The air suspension control module is diagnosed using Super Star II Tester 418-F045 (007-0041B) or equivalent.
The test connector used to communicate with the air suspension control module is located on the RH side of the luggage compartment.
When the tester is connected, the engine is started and the HOLD/TEST button is latched down, the air suspension control module will respond sending a code 10 to the Super Star II Tester which represents "Diagnostics mode entered." If diagnostic trouble code (DTC) 10 is not displayed, go to Pinpoint Test A.
Air Suspension Control Module Diagnostic Trouble Code (DTC) Index
Condition Possible Sources Action

• No communication with the air suspension control module

• CJB Fuse 5 (15A).
• BJB Fuse 8 (30A).
• Circuitry.
• Air suspension control module.

• GO to Pinpoint Test A .

• Unable to enter auto test

• Air suspension control module.
• Circuitry.

• GO to Pinpoint Test B .

• Rear air suspension does not respond to load changes

• Circuitry.
• Air compressor.
• Air compressor inlet tube.
• Air compressor drier.
• Air suspension height sensor.
• Air suspension control module.

• GO to Pinpoint Test C .

• Rear rides low/high

• Circuitry.
• Air spring solenoid.
• Air suspension height sensor.
• Air suspension control module.

• GO to Pinpoint Test C .

• Poor ride quality

• Circuitry.
• Air springs.

• GO to Pinpoint Test C .

• Air suspension warning indicator ON

• Air suspension switch OFF.

• Place the air suspension switch in the ON position.

• Air suspension control module.
• Circuitry.

• GO to Auto Test.

• Instrument cluster (conventional cluster) or lamp warning module (electronic cluster).

• REFER to Section 413-01A (conventional cluster) or REFER to Section 413-01B (electronic cluster), or REFER to Section 413-01C (natural gas cluster).

Unplugging the Connector will cause the Check Suspension light to come on as its listed as a fault as it cant run.

But with it unplugged the compressor shouldnt been able to start. If you want to kill the compressor pull its relay from the engine bay. located above the battery.

But i'd suggest correcting the fault as if those bags do pop your going to end up being grounded. as the rear will drop a fair bit!

SECTION 204-05: Vehicle Dynamic Suspension 2000 Town Car Workshop Manual REMOVAL AND INSTALLATION Air Spring Removal
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.
WARNING: Disconnecting an air line that is connected to the air compressor can cause personal injury or damage to components as high pressure air is vented uncontrolled.

1. WARNING:
   • Do not attempt to install or inflate any rear air spring that has become unfolded to prevent vehicle damage or personal injury.
   • Failure to observe the following procedures may result in a sudden failure of the air spring or suspension system.
   • Any rear spring which is unfolded must be refolded prior to being installed in a vehicle.
   • The air spring refolding procedure should only be used for an air spring which has never supported the vehicle's weight while in the improperly folded position.
   • Improperly folded air springs found on vehicles during pre-delivery inspection or after use must be replaced.
   • Do not attempt to inflate any air spring which has been collapsed while uninflated from the rebound hanging position to the jounce stop.
   • When installing a new air spring, care must be taken not to apply a load to the suspension until springs have been inflated using the air spring fill procedure.
   • After inflating an air spring in the hanging position, it must be inspected for proper shape.
   
   NOTE: The vehicle must be positioned on a suitable lifting device prior to deflating the air suspension system.
   Vent the air suspension system. Refer to Ride Height Adjustments .

1. 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.
   Turn the air suspension switch off.

1. Raise and support the vehicle. For additional information, refer to Section 100-02 .

1. Remove the rear air spring retainer (5A966).

1. Lift the bottom of the air spring off the rear axle (4001).

1. Remove the air spring.
   1. Disconnect the electrical connector.
   1. Compress the quick connect locking ring and pull out the air line.
   1. Remove the air spring.

Installation

1. CAUTION: To avoid damage to the air spring, do not allow suspension to compress before the spring is inflated.
   NOTE: When installing the air lines, make sure the white air line is fully inserted into the fitting for correct installation.
   Install the air spring.
   1. Position the air spring assembly in the frame seat.
   1. Install the spring retainer clip.

1. Seat the bottom of the air spring on the rear axle (4001).

1. NOTE: When installing the air lines, make sure the white air line is fully inserted into the fitting for correct installation.
   Connect the air spring solenoid valve.
   1. Connect the electrical connector.
   1. Connect the air line.
   1. Make sure air spring is in the proper shape.

1. Refill the air springs; refer to Ride Height Adjustments .

here's some info. Do you have a warning light on or does it say "Check Susp"?

Control Module
NOTE: The 4-wheel air suspension (4WAS) control module is also used for the rear air suspension (RAS) system. The internal processor recognizes external circuitry to determine if it is installed in a 4WAS or a RAS system.
NOTE: The air suspension control module is calibrated with information from the air suspension height sensors. A new or swapped air suspension control module requires the ride height adjustment calibration process to be performed.
A microcontroller-based electronic air suspension control module controls the air compressor motor (through a solid state relay), and all system solenoids. The air suspension control module also provides power to front and rear height sensors. The air suspension control module controls vehicle height adjustments by monitoring the two height sensors, 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 is interchangeable between the RAS and 4WAS system.
The air suspension control module monitors and controls the system through a 32-pin two-way connector. The air suspension control module is keyed so that it 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, Air Spring
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 replaced as a unit.

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 the steering column.
Steering Sensor
The steering sensor is mounted inside the passenger compartment on the steering column. It provides steering rate and position to the air suspension control module through two signals.
Pressure Relief Valve
The pressure relief valve (PRV) protects the rear air suspension components by venting the system to a specific pressure in the case of a system malfunction. The system will decrease the pressure to an acceptable level to maintain vehicle height. In the normal operation mode with normal system pressure the PRV is constantly closed and does not have any effect on the system performance or function. The PRV is replaceable without any air lines.
The PRV is located in the rear of the vehicle on the middle of crossmember #5 as a part of the rear air line assembly.

There is one at each wheel. here is some info

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

Suspension Height Sensor Removal and Installation
NOTE: Front shown, rear similar

1. WARNING: The electrical power to 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 LH quarter trim panel. 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.
   Raise and support the vehicle. For additional information, refer to Section 100-02 .

1. Disconnect the sensor arm.

3. Remove the bolts and the sensor.
4.

1. Disconnect the electrical connector.

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Ride Height Adjustments
Special Tool(s) Worldwide Diagnostic System (WDS)
418-F224

New Generation STAR (NGS) Tester
418-F052 or equivalent scan tool
Inflation and Deflation of the Air Suspension System

1. NOTE: Make sure that the air suspension switch is in the ON position
   NOTE: Make sure that a battery voltage of at least 11 volts is maintained while carrying out this procedure.
   Turn the ignition switch to the ON position.

1. Connect scan tool to the data link connector (DLC).

1. Select Air Suspension Control Module under Active Command Mode:
   • VENT FRNT to deflate the front down.
   • LIFT FRNT to inflate the front up.
   • VENT REAR to deflate the rear down.
   • LIFT REAR to inflate the rear up.

Calibration
Ride Height Resetting

1. NOTE: Make sure that the air suspension switch is in the ON position
   NOTE: Make sure that a battery voltage of at least 11 volts is maintained while carrying out this procedure.
   Turn the ignition to the ON position.
   • Exit the vehicle, close all doors and allow the system to vent the vehicle down to kneel height (approximately 45 seconds).

1. With the ignition remaining in the ON position, shift the vehicle into DRIVE and then back to PARK.
   • Exit the vehicle, close all doors and allow the vehicle to pump to trim (approximately 45 seconds).

1. Measure the ride height. For additional information, refer to Section 204-00 .

1. Open the LF door.

1. Connect scan tool to the data link connector (DLC).

1. While outside of the vehicle, select the proper vehicle year, model and engine type.

1. Select 4WAS module.

1. Using the active command mode, vent or lift the vehicle to achieve the correct ride height.

1. Select the "Save Calibration Values (Store Ride Height)" scan tool command to calibrate the 4WAS module.

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