F11 Air suspension bumpy in the morning!

Discussion in '5 Series' started by Gary J, Sep 29, 2020.

  1. Gary J
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    Gary J

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    Hi, I'm hoping someone can help. I have read through similar posts but none seem to have the same symptoms.
    I have a 2010 F11 with rear suspension problems.
    Both air suspension bags have been changed and there is no drop in suspension height or leaking.
    Every morning, within the first mile, the suspension rapidly inflates and then deflates and feels like driving over a testing ground.
    I pull over, turn the ignition off for a few seconds, restart and everything is fine. When I finish work some 12 hours later, I have no faults and everything works perfectly.

    I have changed the solenoid for an Ebay £35 one but it made no difference.

    I have changed the relay but the new one causes the ride height error to show on the dash screen but feels normal, so I think it is causing the system to remain charged with air but isn't active. The fault remains there permanently at all times of day. I have now put the original relay back and the rocky road symptoms return in the morning but not evening's!

    Any ideas?
     
    Last edited: Sep 29, 2020
  2. GunRunner
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    GunRunner WARLORD Site Supporter

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    Hi and welcome to the forum. Not my area of expertise, but someone will be along soon to assist you.

    When you are able, please tell us about yourself and post pictures of your car.
    :nopictures:

    Regards

    Peter R
     
  3. Peter
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    Peter WARLORD Site Supporter

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    Strange. How did it fault to begin with, failed air spring? Would seem like it could be a height sensor issue, if it pumps up and then down again. Strange it is different morning and evening. I assume you lock the car in the day, so car goes to sleep between both uses..

    Peter
     
  4. Gary J
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    Gary J

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    The fault started randomly and about 6 months after changing the air springs. Yes, I lock it day and night so really weird that it just happens in the morning.
    Is the sensor a known fault and if so, is it easy to replace?

    Thanks for your reply, I really appreciate it.
     
  5. JasonH
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    JasonH

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    I think you need to check the ride height sensors and the wiring to them. Are they plugged in properly? Are the wires damaged? Do the sensors look in reasonable condition?

    Then you'll need a multimeter to check the sensor resistance changes smoothly as the arm is moved up and down (disconnect the arm rather than move the car up and down!!).
     
  6. Gary J
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    Gary J

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    Thanks JasonH, I will jack it up tomorrow and follow your advice and report back.
     
  7. Gary J
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    Gary J

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    So, I have taken both sides off to inspect. Both look okay, no obvious sign of damage to the wires or sensors.

    The sensors have a 6 pin connector but only 3 have wires going to them.

    I tested with a multimeter and could only get a reading across 2 pins, both giving a constant 46 to 47 ohms regardless of the sensor position, so I have no idea if they are working or not as I am not convinced I could test them properly.

    At least I now have the part number but none of the local and national motor parts shops can supply, all telling me its main dealer only.

    Any other thoughts?

    Thanks, Gary
     
  8. JasonH
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    JasonH

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    OK, it looks like I may have mislead you a bit. I'm still suspicious of the level sensors and they are basically a potentiometer (variable resistor). However there may be a bit more to them. It looks like they need a 5V supply across 2 pins and then give out 0.5V to 4.5V on the other pin proportional to the ride height.

    If you had diagnostics you could probably just read out the sensor output as you wiggled it - but I assume you don't.

    There will be sources of ride height sensors online but otherwise a main dealer is a good bet. Try the forum sponsor Cotswold BMW for a forum discount and free postage.

    Don't buy the sensors just yet - on a BMW you really need to find the source of the problem before you start changing parts or it gets really expensive.

    To get the correct part numbers go to https://www.realoem.com/bmw/select.do and put in the last 7 digits of your VIN. This gives you the main dealer exploded diagrams and part numbers.

    Here's the full info on your suspension.

    https://www.newtis.info/tisv2/a/en/...nsion/electronic-ride-height-control/2coth0kK

    In the E61 I think the control unit was in the boot under the spare wheel and if water got in there it would pond and cause all sorts of odd issues. On your F11 I wonder if there is a similar issue.

    I think when you changed the relay you put the wrong type in. With the wrong relay,as you suspect, the suspension is disabled and just holds the air that is in there (until it leaks out).
     
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  9. Gary J
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    Gary J

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    Thanks again for your help, I will try to get it diagnosed next week as the ride is unbearable, so must be causing harm to other components too.
     
  10. JasonH
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    JasonH

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  11. Gary J
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    Gary J

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    Thanks for the link to the additional data.

    A) I have had a good look but can't see any sign of water ingress or corrosion to the EHC (I think this is the box mounted to the rear of the spare wheel/battery area) or any other connections linked to the ride height system, so think it is failing component's, rather than water damage.

    B) I didn't change either sensor when I changed the air springs but did notice that both sides have the same part fitted (part number 3714678407503), when I looked yesterday, which struck me as odd, as I had presumed they would be handed.

    I also wondered if there was any way of reprogramming the tolerance band, so is it just a little worn and it is therefore hunting to work within tolerance?
     
    Last edited: Oct 4, 2020
  12. JasonH
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    JasonH

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    You can (and should) use diagnostics to set the ride height when you change anything but you obviously have a problem so I don't think a fudge will work for long.

    Whereabouts in the UK are you. Someone on the forum might be able to assist with diagnostics. ISTA might just tell you immediately what the issue is.

    Have you figured out if you have the old or new sensors? If it's the new type they connect to ICM or BDC so there might be a corroded connector there instead.
     
  13. Gary J
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    Gary J

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    Sadly my knowledge of electronics is pretty basic, so I'm not sure if I can identify what type it is. From the OEM part number check website you linked me to, they actually state a different part number to what I have fitted, so even more of a mystery.
    I am in Norwich

    Thanks again for all of your support
     
  14. Gary J
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    Gary J

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    So I ran the full diagnostic tests over the weekend and the fault code relating to the EHC is 480DB0 Raise control time.
    The compressor runs consistently and quietly. I used the diagnostic kit to manually lower and raise the suspension, which it did without problem, so hopefully not the compressor. Could it be the solenoid valve not responding quick enough to uneven roads when it is cold?
     

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