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.
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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.
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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.
exact same. terrible ride, started about one month ago. Ride control light goes on
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