Need Help re: Level Control System Failure
 

after almost 1.5 year i finally got my first major problem with my E70

the Air suspension on the rear right is bottom out and i got an error saying "Level Control System Failure"..

i wanna DIY and diagnose this issue so anyone can point me to the correct part i should troubleshoot or look at below?

RealOEM.com - Online BMW Parts Catalog

thanks guys

Bmw it's 08 3.0 and it has an air suspension.

not a lot that can go wrong there. you have sensors in the wheel wells that observe the ride height, a compressor in the boot and obviously bellows as springs. it can be any of those. the bellows do have a habit of cracking eventually, esp when they extend due to the car being jacked up. and seeing how it's an '08, they're old enough to perish. check that the compressor works, all air connections are tight, the sensors still in place and the bellows don't leak. that's as far as i would check before getting a pro involved.

Thanks. Can you point me in the realoem how the sensors or compressor looks like? Can all this be accessed underneath the car?

first of all: does the rear of the car sag? does it drive differently? if you have a problem with the pneumatics of it, you'll know very soon.
the compressor is in the back of the car, under the floor. you might have to remove a cover or two to get at it but it's inside, not underneath. the sensors are adjacent to the struts in the rear wheel wells.

also worth considering: have you installed any aftermarket electric parts that might interfere? i used to get a suspension fault message (and other random faults) on an E39 because i put cheap LEDs into the halos. even swapping them left to right gave me completely different errors, all of which disappeared when i put the original bulbs back in.

there are a fair few threads on air suspension DIY, you might want to check those.

Yes the back is sagging on the right side all the way down lowered on one side.

I will try and swap sensors from left to right and see if that fixed it. Will also look at the compressor. Thanks for the pointers.

Do you know how to SEARCH here on the forum? A hundred posts at least on replacing airbags...

I just had this happen to my 2010 and it was the air bag, best to replace both of them at the same time. These are the best in my opinion,
Arnott Industries bags,Part #: 37 12 6 790 078 / A 2642. They come with a life time warranty. You can stick your ear down by the back tires and listen for the compressor or a hissing sound.

update: got a brand new arnott airbag and installation is quick after following their youtube video.. unfortunately after install and deflating both sides it seems like the compressor is not pumping air :(

i removed all under cover on the passenger side and followed the colored pipes (blue and red) and when i start the car the compressor pump is not doing anything (at least i feel like it as there's no noise and airbag is still deflated)..

any other thoughts on how to proceed? or should i get a new airpump compressor too?

PS: was about to look at fuse but the printed diagram i have for some reason i cannot find the fuse #38 to #40 lol. is it in the front of the car?

i'd recommend to disconnect & remove the compressor and try firing it up on a bench by applying 12V directly.

Mike-

So the compressor was working- the suspension would go up, but one side began to drop.

Then you replaced both airbags

Now you have nothing- no compressor, system bottomed out.

Correct?

Ok I removed the compressor and pUT 12v direct and it seems to be working.. wtf!

I checked the fused under the globe box and all seems to be ok.

So bnew bag on one side and a non working air compressor. Anything else I can check before I get a replacement compressor?

@ard nope. I saw the car sagging on the side so I replaced one airbag and deflate the other. After completion now airpump compressor won't inflate both bags :-(

i'd recommend you hold your horses on buying a new compressor for now. the whole function is a pretty simple "if this, then that" scenario. like "if ride height is low, start compressor until ride height is ok". so obviously there's something stopping that from happening. if the compressor works on your bench, there's no reason why it wouldn't work in your car, so the problem is further upstream. have you checked that the level sensors are all working correctly? at this point it's probably wisest to plug into the OBD and try tracing the fault through there instead of blindly throwing more money at it and hoping that it miraculously gets fixed.

What do you mean by start compressor until ride height is ok? Does our e70 has this option or its just automatic when the car starts?

that's how the system works. it's self-levelling. it monitors the ride height and adds or releases pressure accordingly. that's what the sensors are for. they tell the system what the level is. you *have* checked the sensors, haven't you?

I havent. Are those the 2 near the rear shocks with like an L shape arms? How would I go about in checking them if they work?

BTW thanks all for the assistance.

Edit: come to think of it, I might have jack the car too high because i was testing this with 2 wheels removed. I will lower it tomorrow and see if compressor pumps and inflate the bags.

check out the attached wiring diagram. HSHL+/HSHL/HSHL- (left), HSHR+/HSHR/HSHR- (right) are the sensor outputs for high, normal and low ride height for either side. there's obviously also a supply voltage going into the sensors as well. see if the supply voltage even gets to the sensors, your problem could be something as simple as a broken wire. measure supply voltage on both sides, get a reference value, see if it's the same both sides. ideally you should plug into the OBD to monitor I/O activity and see what, if any, signal arrives at the control module.

alternatively, find a car breaker and see if you can grab an identical tried and tested replacement sensor and swap your sensors, see if the problem persists.

i'm presuming you checked the solenoid valves that are part of the compressor assy, to see if the compressor, while it works, actually delivers air where it needs to be or if the pressure release valve might be seized. it's a simple enough system with a fair amount of things that can go wrong.

I bet it will. Vehicle thinks rear is high so no reason to kick on the compressor.

Pretty sure the DIYs mention slowly lowering the rear to allow the compressor to fill up the bags...

Yep you are right :rofl:

As soon as i installed the 2 rear tires and remove the rear jack stand, fire up the car the air pump filled the air bags..

Car is all good now. I'm sorry everyone, I didn't know that the car has an auto level and needs to be lowered to the ground.

Question though, is there a kit for our car to lower it on all 4 lowering springs? Reason I asked is I bought another bag and the 2 alone is already almost $400 new.