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sprinkles08
sprinkles08, ASE Certified Technician
Category: BMW
Satisfied Customers: 21581
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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My 2002 745 leans to the driver side when take off but

Customer Question

My 2002 745 leans to the driver side when take off but straightens up when I stop
Submitted: 6 months ago.
Category: BMW
Expert:  Lou P replied 6 months ago.
Hello, i am going over your info to see how i can assist, i will reply back soon with some info, Lou P.
Expert:  Lou P replied 6 months ago.
ok so the first thing i would check is the level sensor on the left side, make sure the sensor is secured and the link moves freely and is not broken or seized, that can send wrong signals to the suspension computer and make it do all sorts of odd things. Lou P.
Expert:  Lou P replied 6 months ago.
here is the description for your knowledge. 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 ***** ***** 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/sq.s. With a lateral-acceleration signal of 1.5 m/sq.s, the Curve mode is closed. The lateral-acceleration signal is sent by the yaw rate sensor. 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.
Customer: replied 6 months ago.
My 745li has shocks & springs in the rear wound I still have a level sensor and where should I look for it?
Expert:  Lou P replied 6 months ago.
do you have the self leveling in the front? i will see if i can get you a picture
Customer: replied 6 months ago.
My car has eibach shocks & springs front and rear only a year old , car was sitting for 7 month's until I bought a battery and decided to drive it.
Expert:  Lou P replied 6 months ago.
ok, i was under the impression that you had the adjustable suspension, how can you confirm that the left front is actually lowing when taking off? are you sure another part of the car is not raising?
Customer: replied 6 months ago.
Sitting still it's fine ,when I take off the driver side drops and rub the tire's, when I stop car automatically raises level and is level in park
Expert:  Lou P replied 6 months ago.
ok, this is really odd as the front end under load should raise up, something in the rear must be loose to make the front dip down , i will have to opt out as i dont know how much help i can be with this,. another expert should be along soon.
Customer: replied 6 months ago.
Thanks but the front & rear leans to the driver side . I appreciate your help and please pass my problem to another expert.
Expert:  sprinkles08 replied 6 months ago.
Hello and welcome to JustAnswer!Do you still need help?
Customer: replied 6 months ago.
My 2002 745li leans to the driver side only when I take off,leans hard and rubs my tire's, when I stop it levels out . I have shocks & springs front and rear.
Expert:  sprinkles08 replied 6 months ago.
Do you still need help?
Customer: replied 6 months ago.
Expert:  sprinkles08 replied 6 months ago.
Are you able to upload a picture of the vehicle's stance on both sides while sitting as well as where you're seeing the tires hit?
Customer: replied 6 months ago.
No the car only drops when I take off it straightens up level as soon as I stop, when I press the gas to move 10 feet drop hard to drivers side,sets level at idle.
Expert:  sprinkles08 replied 6 months ago.
Are you stating that you have aftermarket shocks on it and the vehicle does not have active suspension?
Customer: replied 6 months ago.
Correct eibach front & rear no air suspension,thats why it's odd car drops when taking off .car was sitting 7 months until I put a battery in it to drive it
Expert:  sprinkles08 replied 6 months ago.
It's implausible that the symptoms you're describing could be possible without an active suppression system, which is why I'd like to see the vehicle's stance while sitting and the physical locations the tires are hitting.
Customer: replied 6 months ago.
Thanks for trying to help, but something has to be controlling the suspension other than my shocks & springs
Expert:  sprinkles08 replied 6 months ago.
That would indicate you have active suspension. If you have mechanical shocks and springs then they are what set ride height.
Customer: replied 6 months ago.
I got a suspension warning 2 years but it never came up again on my dash
Expert:  sprinkles08 replied 6 months ago.
That means you do have active suspension. A scan tool capable of communication with the suspension module will be need to diagnose the issue, you almost certainly have a bad height sensor.
Customer: replied 6 months ago.
Thanks for your help.
Expert:  sprinkles08 replied 6 months ago.
You're welcome!