I have a 2000 BMW 528i sport wagon with self leveling rear suspension and the air compressor run a lot

You need to check a few things. Do you ever hear the air compressor at the rear of the vehicle running?
If so, does it run continuously with the ignition on? (that will mean there is usually an air leak either in one of the rear shocks or the air lines/connectors).
If not, either the compressor, or the compressor relay, level switch and/or the fuse may be shot and each will have to be checked.

The compressor is 600 bucks. If you can hear it running, then one or more plastic air lines going up to each shock is cracked . The level sensor may not be turning the compressor on. If you have experienced high water or a lot of snow and salt the system needs to be looked at to see what failed.

Duplicate question

BMW 5 Series (E39) Service Manual: 1997-2002
2003 ' Bentley Publishers ' English ' ISBN: 083760317X ' Pages 1002 ' File type: PDF ' 44.37mb

This Bentley Manual is the only comprehensive, single source of service information and specifications for BMW 5 Series (E39) cars from 1997-2002. Whether you're a professional technician or a do-it-yourself BMW owner, this manual will help you understand, maintain, and repair every system on 5 Series cars.

BMW 5 Series (E39) Service Manual: 1997, 1998, 1999, 2000, 2001, 2002
525i, 528i, 530i, 540i Sedan, Sport Wagon.

It is normal for some cycling of the compressor as the ride heights change and the compressor vents and fills air springs. Info:

Air Compressor
The air compressor:

• Is not interchangeable with the rear air suspension (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.
• The drier may be replaced separately.
• The drier has dual ports and is not interchangeable with the RAS drier.

The vent solenoid:

• Allows air to escape from the system during venting actions.
• Is part of the air compressor cylinder head.
• Shares a common electrical connector with the air compressor motor.
• Is enclosed in the cylinder head casting, which forms an integral valve housing that allows the valve tip to enter the pressurized side of the system.
• Has an O-ring seal that prevents air leakage past the valve tip.
• Opens when the air suspension control module determines lowering is required.
• Provides an escape route for pressurized air when system pressures exceed safe operating levels.
• Has a 1792 kPa (260 psi) internal relief valve.
• Is installed with the air compressor as a unit.

Compressor Relay
A solid state relay is used in the air suspension system for compressor control. The relay incorporates a custom power metal oxide semi-conductor field effect transistor (MOSFET) and ceramic hybrid circuitry. The relay switches high current loads in response to low power signals and is controlled by the logic of the air suspension control module.
The compressor solid state relay is energized by the air suspension control module to have high current flow from the battery to the compressor motor.
Control Module
NOTE: The 4WAS control module is also used for the 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 the vehicle and related components.
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.

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.

1. If the concern remains after the inspection, use New Generation STAR (NGS) Tester connected to the data link connector (DLC) to retrieve continuous diagnostic trouble codes (DTCs) and to execute On-Demand Self-Test diagnostics for the air suspension control module.
   • If the On-Demand Self-Test is passed and no DTCs are retrieved, go to the Symptom Chart to continue diagnostics.
   • If DTCs are retrieved, go to Air Suspension Control Module Diagnostic Trouble Code (DTC) Index in this section.
   • If the air suspension control module cannot be accessed by NGS Tester, go to Pinpoint Test A.

Self-Test
Verify that the following conditions are met before running the On-Demand Self-Test.

• All doors, liftgate, and liftgate glass must be closed.
• The transmission is in PARK.
• The BPP switch is not pressed during the test and the parking brake is not set.
• The accelerator pedal is not pressed during the test.
• The vehicle is not in 4L mode.

1. Fulfill the pre-conditions.

1. Install a battery charger for the On-Demand Self-Test to prevent battery drain.

1. Run the air suspension On-Demand Self-Test.

1. Record all listed DTCs.

1. Retrieve stored DTCs.

1. Troubleshoot any On-Demand Self-Test DTCs first.

1. Retest and clear DTCs after repairs.

hi,i own a bmw 750i,and went over a hump back bridge to fast and left the ground a bit.since then the rear suspension is jacked right up high permanently and makes a screeching sound like gas is escaping...any ideas??

If you have a hole or crack in your airbag the compressor has to work extra hard to try to blow it up (like blowing up a balloon with a hole in it) I would recommend checking out strutmasters.com they have some great kits for the Ninety Eight. There kits will eliminate any problems with the suspension. It is a permanent fix. these convert you from the airbag to a powder coated American made steel coil spring that is guaranteed to last the life of the car. And for a very affordable cost. I added the link below so you can check it out.
http://www.strutmasters.com/oldsmobile-suspension-parts-s/85.htm

Hopefully this will help

Good Luck!!!

your leveling sensor will be on the rear suspension it will hook to one of thwe control arms.
you can un hook the arm and push it all the way down and should let air out

Check for pressure out of the air pump. If there, then the problem is a blown seal in the shock.

Hi,

Your concern is your BMW displays the message "SELFLEVEL SUSP. INACT" which indicates that the car's computer detects a problem with your active suspension system. Self-leveling is standard to most late model BMWs. It works on a pump, an air system and a computer that tells which suspension gets how much height, ride stiffness and other suspension settings.

Your concern is a known issue though not that fairly common. Technically, the best would be to contact your dealer or if in The USA, BMW of North America, LLC. call (800) 831-1117 or email [email protected].

You may want to mention a possible problem with the firmware/software of the EHC (Electronic Height Control) Control Module. They may want to recode (flash). It is also possible to have air leaks in the system specially on the suspension bladder.

Other things you can check are tire pressure (30PSI), see if your ride is a bit stiff/hard now compared to before the earning displayed showed up, handling difficulty, loopsided/tilted level among others.

Incidentally, if there is nothing out of the ordinary in how the car ride, handle or drive, it may just be a systems glitch. Try jockeying the key to ON/OFF a couple of times.

Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards.

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