Help from the gear heads urgently needed?

[Shang]

When I replaced my rear bags a few months ago, I had to actually drive the vehicle around the block before the system came on and cleared the warning on the dash. Also after using adjustable links on the rear sensors to lower the vehicle I needed to start the car and drive a few feet before it would make any adjustments.

FYI, I drove my X5 home from work with one bag empty on the freeway. It's just sitting on the bumpstop. While its definitely not good for it, it was fine. You might want to wear a kidney belt though.

[TerminatorX5]

the aircompressor will not run without the engine running - i can't paste the info from the BMW indicating this, as something is up with my Java on my computer...

you can lower the car with engine off and all the doors closed, but you need engine on and the doors closed to pump the car up... once i figure out my Java, i wil lbe able to pull that info and post, unless somebody will post it before...

if none of the above does not help, check the fuses and the relays - again, without that Java thing i can't pull the specific info...

[TerminatorX5]

Self-levelling suspension

The self-levelling suspension is a further development of the EHC system as already used on the 5 Series and X5.
Operating principle of the control module

The control module processes the following signals and K-CAN messages:

• Ride-level height of vehicle from ride height sensors located at the rear right and rear left.
• Load-cutout signal (of power management battery voltage)
• Terminal 15 ON/OFF (K-CAN message terminal status)
• Vehicle speed (K-CAN message dynamism)
• Lateral acceleration (K-CAN message dynamism)
• Engine-running signal (K-CAN message driver display, engine)
• Information on the flap status (K-CAN message flap status)

The control module decides case by case whether there is a need for intervention to balance out changes in load. It prevents intervention in the case of other causes. This makes it possible to gear the intervention to each situation as regards optimum frequency, target height, tolerance thresholds and battery load.
In addition to handling the self-levelling suspension, the control module has the task of monitoring the system components, saving and displaying faults.
System functions

The task of the self-levelling suspension is to bring the vehicle ride height at the rear axle back to the target level if the load changes. The self-levelling suspension works by feeding or extracting air into or out of the bellows. The height sensors provide the control module with information on the heights of the left-hand and right-hand sides of the vehicle. If the heights are outside the specified tolerances, the system intervenes using the air supply unit to set the nominal ride-level height.
Changes to the load mainly take place when the vehicle is at a standstill, before or after a journey. In order to load the vehicle, the doors or trunk/rear hatch have to be opened. The system is therefore enabled when a door or the trunk/rear hatch is opened and only switches itself off 16 minutes after the vehicle has been vacated (load-cutout signal).
In order to distinguish load changes from other disturbances such as road irregularities, the height signals are filtered through two different lowpass filters with different limit frequencies (high and low frequencies). The filtering is explained in the HGK E39 drive/suspension. Various signals and messages indicate the different driving conditions to the control module, which switches into various operating modes depending on the condition.
Intervention modes

The operating modes intervene depending on the vehicle condition or suppress interventions. Intervention modes are:

• Sleep
• Pre (pre-/after-run)
• Post (post adjustment)
• Normal (engine running)
• Drive
• Curve (driving in a curve)
• Kerb
• Lift (workshop platform)
• Transport
• Assembly Line Mode

Sleep

The Sleep mode is the initial state for interventions. In the Sleep mode, no intervention takes place.
Pre (pre-/after-run)

In the Pre mode, the load-cutout message of the power module initiates a time- controlled pre-run and after-run. The load-cutout signal is set by activities on the vehicle such as pressing the door handle or operating the central locking system and output on the K-CAN.
In the case of ignition key position terminal R or terminal 15 or engine on signal, the signal is set permanently.
If the vehicle is parked, the load-cutout signal remains set for approx. 16 minutes after the last action (e.g. door opening). If a door status changes within this 16 minutes, the after-run time is restarted. When this after-run time expires, the message 'switch off consumers' is sent and the control module switches for 1 minute into the Post mode before it goes into the Sleep mode.
In the Pre mode, the vehicle can only be raised to its specified height if the level drops significantly below the specified height. The intervention tolerance range is currently - 40 mm from the mean value. This intervention tolerance ensures that the vehicle is only raised for heavier loads to increase ground clearance before driving off. Smaller payloads only lead to small amounts of spring travel which are only balanced out after the engine has been started. This setting reduces the load on the battery.
The vehicle is lowered when the mean value of the two height signals > 0 mm AND one side is above + 10 mm.
For the decision regarding intervention in this mode, only the mean value of the two height signals (fast filter) is analyzed.
Interventions that were started in other modes are continued with the internal tolerance ranges that apply to these modes.
There is no inclination detection in the Pre mode.
On return to the normal mode from the Drive mode, intervention remains blocked until a door is operated. This prevents intervention when the vehicle is at traffic lights, for example, and the pitching motion at the rear axle causes the height to rise above the mean value.
Post

The Post mode is used to balance out any visual inclination before entering the Sleep mode. It is a mode for post-adjustment. The Post mode is limited regarding time (currently coded for 1 minute). The Post mode is only run when the engine has been running. Without previous engine operation, a direct switch is made from the Pre mode to the Sleep mode.
Intervention takes place within a narrow tolerance range of 7 mm. At 5 mm, the intervention is stopped. The fast signal filter is used. In the case of an inclination (kerb detection), intervention is at the specified heights applicable to this case.
Normal

The Normal mode is the starting point for the normal operating status of the vehicle. It is reached by means of the 'engine running' signal.
The fast filter is used with a narrow tolerance range of 10 mm. A narrower tolerance range than in the Pre mode can be used because the battery capacity does not have to be protected.
In the case of a vehicle inclination (kerb detection), intervention is at the specified heights applicable to this case.
Drive

The Drive mode is activated when a speed signal of > 1 km/h is detected. The intervention is activated by a slow filtering if the signals, as in this operating mode only the height differences caused by the negative force of the vehicle and reduction of the vehicle mass due to fuel consumption have to be balanced out. The intervention itself, however, takes account of the fast filtered heights. For the end of control/intervention, the slow filters are reinitialized.
Curve

As rolling motion has a direct influence on the measured heights, longer driving in a curve with a corresponding roll angle would lead to undesired intervention in spite of the slow filtering of the Drive mode. On completion of the curve, this would lead to an inclination and renewed intervention. The Curve mode prevents this intervention in that the slow filtering is halted when driving in a curve is detected and any intervention that might have been started is canceled.
Driving in a curve is detected in the case of an incoming lateral-acceleration signal of > 2 m/s2. With a lateral-acceleration signal of < 1.5 m/s2, the Curve mode is closed.
The lateral-acceleration signal is sent by the yaw rate sensor.
Kerb

Kerb
Detecting this state prevents the inclination produced when one side of the vehicle rises on an obstacle with one wheel from being balanced out. Compensation would, after driving off the obstacle, lead to a renewed inclination of the vehicle and a renewed intervention.
The Kerb state is detected when the difference in height between the left-hand and right-hand sides of the vehicle > 24 mm.
If the vehicle is loaded or unloaded on an inclination, the control module analyses the value of the middle of the car between the rear wheels. The value is calculated in the control module from the changes in height of the right-hand and left-hand spring paths.
If the value of the spring travel or rebound at the calculated center of the rear axle lies outside the tolerance range of 10 mm, self-levelling is triggered. The left-hand and right-hand sides of the vehicle are raised or lowered in parallel. The difference in height between the two sides remains. As soon as the control module goes into Drive mode, the Inclination mode is deleted.
Lift

In order to prevent intervention in the case of a wheel change or work on the workshop platform, there is the Lift mode.
If this mode is detected, all interventions are prevented until the car jack is removed or the vehicle is lowered from the workshop platform.
Detection takes place when the permitted rebound path of 55 mm is exceeded. If the left-hand and/or right-hand height exceeds this rebound path, the situation wheel change/workshop platform is detected.
The workshop platform situation is also detected if the vehicle is raised slightly, the rebound path of 55 mm has not yet been reached, the vehicle wants to intervene, but does not lower. If the drain valve is activated and the vehicle does not lower, the workshop platform situation is detected after a certain time and this height is saved. A reset is carried out if the vehicle is again 10 mm under this stored height OR Drive is detected.
Transport mode

The Transport mode is set by means of diagnosis activation. It serves to increase the ground clearance to ensure safe transport of vehicles on transporters. The specified height of the vehicle is raised by 30 mm in this mode.
When this mode is activated, the symbol for the air suspension function is displayed in the instrument cluster in the variable indicator light and the text message ”Self-levelling suspension failure” is output in the Check Control display to indicate this special mode.
There is no intervention in this mode, as there are no changes to the vehicle mass during transport.
The Transport mode is deleted only by means of diagnosis activation.
Assembly Line Mode

The Assembly Line mode is set for the assembly line to prevent regulating operations. The fault display is activated and shown in the variable indicator light by a symbol and in the Check Control display with the text message ”Self-levelling suspension failure”.
The Assembly Line mode is deleted only by means of diagnosis activation.

[TerminatorX5]

this applies to rear end suspension only:

Rear axle air suspension (level control)

Introduction

The rear axle air suspension has the task of maintaining the height of the vehicle body as precisely as possible at a pre-defined level under all load conditions. The almost constant level means that the geometric data of the rear axle suspension, such as camber and toe-in, remain unchanged regardless of payload. For the first time at BMW, the entire rear axle load is born by air suspension with the optional extra level control in the E39. This system controls the rear axle level automatically, and without the driver being able to interfere.
The rear axle air suspension is configured so that unnecessary control is largely avoided.
The system offers the following benefits:
- control is independent of vehicle engine
- single-wheel control is possible
- differentiation between load and vehicle condition
- uneven loads can be recognised and compensated for
- compatible with self-diagnosis
- control is interrupted in corners and/of when loading



The entire system consists of the following components:
- Air supply system (LVA)
- Two pneumatic suspension struts
- Two height sensors on the rear axle (left/right)
- Electronic control unit
- Warning lamp (standard instrument cluster) or text display (high instrument cluster)

The system components are described below:
Air supply system (LVA)

Theair supply system consists of
- Cover with integrated interior noise insulation
- Compressor
- Compressor relay
- Solenoid valve block
- Air pipes, incl. distributor block
The compressor supplies a maximum operating pressure of 13.5 bar. The compressor is mainenance-free. The electric motor is a DC motor.
Important!
To prevent the compressor being thermally overburdened, the time that the electric motor is switched on is monitored: Maximum 8 minutes !
The compressor is supplied with current by the compressor relay.
Important!
the compressor relay cannot be changed! if the compressor relay is damaged, the entire LVA must be changed.
Solenoid valves are used to control the air flow from the comressor to the suspension struts and vice versa. Each pneumatic spring is allocated one valve. The valves can be activated indiviually.
The pneumatic lines (air pipes) create the connection between the solenoid valve block and the distributor block. The pipes are color coded: blue for right, red for left. A distributor block is used as a pneumatic interface between the LVA and the air pipes to the suspension struts. This is also color coded on the connections for the air pipes. the distributor block is located in the luggage compartment under the right-hand side member.
Pneumatic suspension struts

The pneumatic suspension strut consists of an air reservoir, a bellows and an additional volume. The bellows forms the air-tight and movable connection between the air reservoir and the suspension strut and, with its effective interior surface over the prevailing air pressure, carries the vehicle load.
Height sensors

The height sensors are located at the rear right and rear left on the respective radius arm bearing block. They are linked by a coupling rod through the rear axle arms. From the respective deflection angle, the control unit receives information of the current height of the vehicle. Both sensors work according to the Hall principle.
If the vehicle is equipped with the optional extra headlight range control, the right-hand sensor configured as a double sensor.
Control unit

The control unit is installed in its module box in the luggage compartment beneath the right-hand side member.
Signal lamp/Text message

The air suspension system signal lamp is centrally located in the standard instrument cluster next to the ASC display. On the high instrument cluster, any error messages are given in the text line.
How the entire system works

>The system is controlled by a microprocessor, starts working when a door or lid is opened, and continues until approximately 16 minutes after the vehicle is left. The electric drive of the compressor makes the system independent of the vehicle engine.
The following signals are evaluated in the air suspension control unit:
- Consumer cut-off signal
- Height, left
- Height, right
- Terminal 15
- Road speed
- Engine ON/OFF
- Information on the status of the doors and trunk lid
The vehicle height is determined by the amount of air in the pneumatic suspension strut. The air quantity in the pneumatic suspension strut is adapted for differing vehicle loads by the compressor and/or the valve in the air supply system being activated.
The LVA supplies air from the luggage compartment to the bellows through the solenoid valves, which are switched by the control electronics, until the specified level is reached.
A pressure check valve protects the system against excessive build up of pressure.
When lowering (vehicle load is reduced), the appropriate solenoid valves and the outlet valve are activated by the electronics. The air flows unhindered into the surrounding area.
Important!
The system can only work properly if the following points are guaranteed: The assembly line mode and the transport mode must be deleted and the height offset properly carried out! Instructions how to delete the assembly line mode and the transport mode, and how to carry out the height offset can be found in the diagnosis program under the heading "SERVICE FUNCTIONS". When the assembly line mode and/or the transport mode are deleted, the height offset must be carried out!
The safety concept is designed to prevent a system malfunction, especially inwanted control processes, by monitoring the signals and parameters relevant to its operation.. If faults are recognised, the system dependent on the component affected is switched off. The driver is informed of the fault by a signal lamp or a message in the instrument cluster. Faults recognised are stored in the fault memory. Up to three faults can be stored.
Control

Both sides of the vehicle are controlled individually, i.e. the comparison specified actual value is also carried out for both sides of the vehicle individually. When the control system raises the vehicle, the permissible time that the compressor is switched on is monitored.
Non-level surfaces

A non-level surface (vehicle stationary) means when one wheel is resting on an obstacle while the other three wheels are on one level. As such an non-level surface is not compensated for, there is no opposite lean when the vehicle is driven from the obstacle. If the vehicle is heavily laden in this condition, the system will operate to ensure that ground clearance is not impaired. A non-level surface is recognised only in normal or trunk mode and so long as no speed signal is received from the control unit.
Types of control

The system distinguishes between the following types of control: pre/post running mode, normal mode, trunk mode, assembly line mode and transport mode.
pre/post running mode

In the pre/post running mode, the vehicle can only be raised to its specified height if it drops below the specified height in the middle by 40 mm. This reduces the load on the battery before starting the engine, as it only raises the vehicle for heavier loads to increase ground clearance before driving off. Smaller payloads only give short spring deflections; it is thus sufficient to compensate for this inly after the engine has been started.
Normal mode, trunk mode

In normal or trunk mode, the specified height is maintained. In normal mode, the load on the rear axle caused by, for example, the fuel tank gradually emptying during a journey, or by the aerodynamic lift on the rear of the vehicle caused by high speeds, are compensated for. In the trunk mode, brief changes in load while the vehicle is stationary and the trunk lid open, are compensated for.
Assembly line mode

In its delivery state, a new control unit is in assembly line mode, i.e. the control unit is de-activated. Control processes are not carried out, the safety concept only works with limitations. The fault display is activated in the intrument cluster.
Important!
It is only possible to delete the assembly line mode with the diagnosis program (SERVICE FUNCTIONS) !
After the assembly line mode has been deleted, the height offset must be carried out. How this is done can be found in the diagnosis program Menu SERVICE FUNCTIONS, "Height offset".
Transport mode

The transport mode effects a raising of the rear end of the vehicle by about 30 to 40 mm to prevent damage to the vehicle underside during transportation from the factory to the dealer. No control processes are carried out. the fault display is activated in the instrument cluster.
Important!
The transport mode can only be deleted with the diagnosis program (SERVICE FUNCTIONS) ! For the purposes of renewed transportation, the transport modecan be activated (SERVICE FUNCTIONS). This is independent of whether or not the transport mode was already activated.
After the transport mode has been deleted, the height offset must be carried out. How this is done can be found in the diagnosis program Menu SERVICE FUNCTIONS, "Height offset".
Note on failure of the K-bus

If the control unit receives no signal from the K-bus, the last signals received (e.g. doors, road speed) remain valid and the control unit remains in the last mode selected until it is de-activated by the consumer cut-off signal. The next time the engine is started, or whenever the engine is started after a communications breakdown, the control unit will remain in pre/post-running mode and the driver is informed of the fault by a fault message in the instrument cluster.

[X5Ghost]

Ok, we'll I thought I'd better post and follow up on this. First I want to thank all who posted suggestions and ideas to try. Unfortunately, none of them worked

Because I was squeezed for time (had to catch a flight), I ended up driving the car 3 miles to a specialty BMW auto repair shop near my house, dropped it off at night, and left a note for them to take care of it and that I hope to get it back when I return. The drive there with none pressurized rear bags was brutal, I was driving 5mph!! If you walked next to the car, you get there faster However, this was important and key in helping not destroy the air struts bump stops. The shop did exactly what I asked them to do. With a GT1, reset the error and initiate the bags filling process It worked and everything is back to normal now

In summary, I guess you can drive (well, I did) with newly installed rear air struts even if they are not pressurized but you have to be extremely careful minding every bump on the road. If you decide do so, you do it at your own risk. I'm just sharing my experience.

Smooth ride everyone and thx for chiming in. Hope this helps someone in the future.