Front suspension not working on my 2004 rx330 with electrically modulated air suspension

There is a relay an there is a control module that controls everything in the air suspension system an ride height sensors an related wiring ! The control module can have diagnostic trouble codes stored in it's memory as to what the problem could be ! Here are some of the basics to check !
Inspection and Verification

1. Verify the customer concern.

1. NOTE: If the door ajar indicator is illuminated when all doors, liftgate, and liftgate glass are closed, the air suspension will not work correctly. Repair door ajar indicator; refer to Section 413-01 . Visually inspect for obvious signs of mechanical and electrical damage.

Visual Inspection Chart Mechanical Electrical

• Restricted suspension movement
• Excessive vehicle load
• Cut, severed, crimped air line(s)
• Unmounted height sensor(s)
• Damaged front air spring(s)
• Damaged rear air spring(s)

• Central junction box (CJB) fuses 11 (10) (later built vehicles), 20 (30A), fuse 27 (5A), and fuse 111 (50A)
• Loose, corroded, or disconnected connectors
• Air suspension service switch is in the OFF position
• Damaged solenoid valve(s)/height sensor(s)

1. If the inspection reveals an obvious concern that can be readily repaired, correct the concern before continuing with Inspection and Verification.

1. NOTE: The 4WAS module is also referred to as the Vehicle Dynamic Module (VDM). If the concern remains after the inspection, use the scan tool connected to the data link connector (DLC) to retrieve continuous diagnostic trouble codes (DTCs) and to execute On-Demand Self Test diagnostics for the 4WAS module.
   • If the On-Demand Self Test is passed and no DTCs are retrieved, GO to Symptom Chart to continue diagnostics.
   • If DTCs are retrieved, go to the 4WAS Module Diagnostic Trouble Code (DTC) Index in this section.
   • If the 4WAS module cannot be accessed by the scan tool, Go To Pinpoint Test A .

Wheel Air Suspension (4WAS) Module 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 4WAS module Go To Pinpoint Test C . B1318 Battery voltage low 4WAS module Go To Pinpoint Test C . B1342 ECU is defective 4WAS module INSTALL a new 4WAS module. REFER to Air Suspension Control Module . SET the ride height. REFER to Ride Height Adjustments . CARRY OUT the pneumatic test. TEST the system for normal operation. B1566 Door circuit failure 4WAS module REFER to the Symptom Chart. B2477 VAPS II steering assist curve not complete 4WAS module REFER to Section 211-00 . C1445 Vehicle speed signal circuit failure 4WAS module GO to Symptom Chart . C1724 Air suspension height sensor power circuit failure 4WAS module Go To Pinpoint Test D . C1725 Air suspension front pneumatic failure 4WAS module Go To Pinpoint Test E . C1726 Air suspension rear pneumatic failure 4WAS module Go To Pinpoint Test E . C1760 Air suspension rear height sensor signal circuit failure 4WAS module Go To Pinpoint Test F . C1770 Air suspension vent solenoid output circuit failure 4WAS module Go To Pinpoint Test G . C1790 Air suspension LR air spring/shock solenoid output circuit failure 4WAS module Go To Pinpoint Test H . C1795 Air suspension RR air spring/shock solenoid output circuit failure 4WAS module Go To Pinpoint Test H . C1830 Air suspension compressor relay circuit failure 4WAS module Go To Pinpoint Test I . C1840 Air suspension disable switch circuit failure 4WAS module Go To Pinpoint Test J . C1873 Air suspension RF air spring solenoid output circuit failure 4WAS module Go To Pinpoint Test H . C1877 Air suspension LF air spring solenoid output circuit failure 4WAS module Go To Pinpoint Test H . C1881 Air suspension RF height sensor circuit failure 4WAS module Go To Pinpoint Test F . C1889 Air suspension LF height sensor circuit failure 4WAS module Go To Pinpoint Test F . C1897 Steering VAPS circuit loop failure 4WAS module REFER to Section 211-00 . U1950 UBP communication bus fault 4WAS module REFER to Section 418-00 . C1964 Air suspension compressor actual run time exceeded allowed run time 4WAS module 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) 4WAS module REFER to "Clearing DTC C1990 or C1991". C1991 Plant ride height setting and/or tests incomplete 4WAS module REFER to "Clearing DTC C1990 or C1991". U2235 4x4 mode status invalid 4x4 control module REFER to Section 418-00 . U2306 Transmission PRNDL indicator or vehicle speed signal invalid Instrument Cluster (IC) REFER to Section 418-00 . This is a very complex system ,you need a factory scan tool or one that is equal to it ! It could be a fuse a wiring issue a sensor or the module , relay etc... You may want to take this to a ASE repair facility or the dealer !

Looks like it.
Go to each corner of the car, press it down as much as you can and let go quickly. The corner should bounce up a little, down a little and then stay at the mid point - that is a 1.5 bounce. If the car is bouncing more 1.5 times or doesn't bounce at all, then the shock at that corner is bad and need to be replaced.

Shocks don't have a valve for the driver to fill with air. They need to be replaced with new ones.

Based on what you describes, the back corners will not press down and of coarse will not bounce - a definite shocks problem that need to be replaced.

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.

Check the system for air leak.

A GM dealer can tell you if you give him the VIN number, but the simplest way is to check one of the rear struts for an electrical connection (will also have a leveling air line connection). If there is one, you have a road sensing suspension (RSS) with rear leveling capability - if not, just air shocks. If you have RSS, these struts are very expensive and notoriously unreliable, and you may want to replace them with air shocks. However, if you do this you will have to trick the RSS into thinking they are still there by terminating each electrical connector with a resistor (see the Cadillac Forums website).

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

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Visual Inspection Chart Mechanical Electrical

• Restricted suspension movement
• Excessive vehicle load
• Cut, severed, crimped air line(s)
• Unmounted height sensor(s)
• Damaged front air spring(s)
• Damaged rear air spring(s)

• Battery junction box (BJB) fuses 20 (30A), fuse 27 (5A), and fuse 111 (50A)
• Loose, corroded, or disconnected connectors
• Air suspension service switch is in the OFF position
• Damaged solenoid valve(s)

1. If the inspection reveals an obvious concern that can be readily repaired, correct the concern before continuing with Inspection and Verification.

1. If the concern remains after the inspection, use the scan tool connected to the data link connector (DLC) to retrieve continuous diagnostic trouble codes (DTCs) and to execute On-Demand Self-Test diagnostics for the 4WAS module.
   • If the On-Demand Self-Test is passed and no DTCs are retrieved, GO to Symptom Chart to continue diagnostics.
   • If DTCs are retrieved, go to the 4WAS Module Diagnostic Trouble Code (DTC) Index in this section.
   • If the 4WAS module cannot be accessed by the scan tool, Go To Pinpoint Test A .

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have your shocks checked. air suspension provides ride height and shocks control bounce from road bumps

Remove battery, remove windshield washer bottle, remove air compressor and disconnect both air lines from the compressor dryer. Make sure compressor electrical wiring is plugged in, install battery, turn suspension switch to ON, turn ignition switch to the ON position, close all door and the compressor should come on and completely lower the whole truck. Once the truck is completely down, turn the ignition OFF, remove battery and connect both air lines. Install battery ensure electrical wiring is plugged in, turn ignition switch to ON, the compressor should come on and raise the vehicle to the correct ride height.

The front suspension, is not air managed. If the front end is bouncing , replace the front strut/shock units. Hope this helps

SOunds like a broken shock, or bad strut. Air bags or not, struts and shocks are what control bounce.