Air suspension having problems

[Bch06]

Hi everyone, I’m new to this forum, Thank you all for the information I have received from here.

I have an X5 2014 f15 which is showing me an error “chassis function restricted” so I have done the following.

1-Both air bags have been replaced previously 3 months ago when the car dropped down to the ground level.

Recently the car has lifted itself from rear quite high so I did a test on ISTA D which showed me “front left vertical acceleration sensor” so I changed that

Now the chassis function restricted error is still there

I have also used the soapy water to check if the solenoid valve has any leak, however there is no leak.

So I removed the fault codes, and went on a ride however the error came back so this time it’s showing me a different code which is 480DB4 “control time rear left”

NOTE: The car doesn’t deflate with the ista D I have to deflate it manually by disconnecting the air pipes which goes to the Air spring, and also doesn’t inflate when I switch on the car, so I inflated with the ista D and it works.

So my question is do I need to change the air compressor? Or it might be something else? Any suggestions?

Thank you in advance.

[Leslie]

I did see this a while ago when strange things happen with air suspension , maybe some water has got in the compressor with all the recent rain and standing water ? seems the beads stick together and the compressor cant vent .Not much in the basic circuit usually bags a, solenoid , couple of level sensors and compressor

https://www.youtube.com/watch?v=dUDDH3mtjr8

[Bch06]

Thank you for a quick reply, I am planning to open the compressor tomorrow morning I have also ordered the silica gel, I hope I get them delivered tomorrow during the lockdown in England.

[Leslie]

It's definitely worth a look before blowing a few hundred on a new compressor as it is running and creating pressure , mine had a dent in the cylinder head where the piston hit it so was a bit terminal

[Bch06]

Ok so I ran the test on Ista D, strangely there are new codes please have a look in the pictures, I have also opened up the air compressor, there are no signs of moisture or any corrosion.

I put the air compressor back on however the vehicle won’t inflate itself, so I had to run the inflate
procedure with ista D, but and went on drive but again the rear is lifted and it looks ugly also the ride was very bumpy. I’m running out of things now.

Could it be the ICM unit? Or the VDC?

Please help me I’m sick of this car

[Leslie]

That looks fine to me ,It sounds like you have a control issue the system doesn't know where it is at , when you commanded it by software it just kept pumping as it isn't seeing the level so is lifting too high and too high pressure in the bags causing a very bumpy ride is that the issue ?
check that the link arms on the back level sensors that attach to the swinging arms has not become detached as that is what it would use to tell the compressor to start and stop pumping. If it has broken off move it and see if it pumps then with the key in and be careful where your hands are at !!!!!!!! If the compressor can be commanded to run it doesn't sound like it is the issue.

Id start with left rear by the codes ...
Is this a 2 airbag car with ordinary dampers not the electronic ones ?

[Bch06]

Thank you Leslie for your reply, I have checked all the ride height sensors they all seems to be fine, have a look in the pictures.

I have also done the ride height calibration and reduced the numbers to 700mm on each wheel so the drive was good and the car is not lifting itself higher, however I’m still getting the “chassis function restricted” warning on the dash, so I connected the ista I’m still getting the ICM errors.

[X5Sport]

Why is Transport Mode on? I thought that was only used when the cars were being ferried from factory to Dealer. That places limits on the suspension controls. Just a thought.

[Bch06]

So how do I switch it off?

[X5Sport]

It’s a coding change normally done by the Dealer as part of the PDI. It’s not unknown for cars to randomly switch it back in again for no obvious reason when repairs have been done. Not having used the tool you have, I can’t say how it’s done but someone on here may know.

[Leslie]

Not much to go with the codes , can you look at each sensor signal and see if they are reading what you would expect as it is reporting a signal invalid but not saying any sensor (Never used ista ) Can the sensors on these flip over like earlier cars if they go too high and then operate in reverse?

[Alan Gunn]

Transport mode will stop the windows and the wipers from working i think but not sure about the suspension.
My e53 is showing suspension inactive but only since it was jacked up on the mot but not plugged the scanner in yet.
These cars have minds of there own i think and like to p1ss us off from time to time (passed the mot as he never noticed the dash warning when out doing the brake test).

[Bch06]

Good news, since the ride height adjustment I have been driving the car, and the dive has gone back to normal, so I connected ISTA to read the codes, all the ICM codes have disappeared, the only code I was getting was the “transport mode active” so I tried to delete, but it wasn’t deleting, ISTA keep showing a message that I need to put the car in ACTIVE PAD.

So when I clicked on the delete transport mode I got the same message so I started the car and somehow the transport mode deleted, yayyy

I then retested the car and there were no codes. I went on a long drive on the way back to home I got the “Chassis Function restricted” again

I tested the car again and I got the error code 480DB4 “ “control time, lowering, rear left” now either it is the level sensor which is faulty or the compressor valve block.

Any thoughts?? Thank you again for the help so far.

[Leslie]

Nightmare lol the system is trickier than I thought I could understand a code for lifting time as that would suggest a leak or low pressure from the pump , I'm not even sure the system really does do any lowering But the fact it says control time means it is just taking too long to get there but may well still get there just too slowly. I suppose if the solenoid was passing it would keep adding air to the system
If the car is level my opinion would be the sensors are working as they need to be to tell the car what height it is at.I believe they may be the same part either side so could be swapped over but that still may not tell you much if say the left side is used for ride height time based checks only
Is there anywhere in that software you can look at the control time and see what its set to for each side incase one side is way less than the other ? If its measured it must be in there somewhere ?

You could disconnect the left rear sensor from the control arm and move it in direction as if car had lowered and see what happens as just because its reading when stationary it doesn't mean the signal isn't disappearing on a bump when the arm is moved .

[Bch06]

Finally everything is resolved, I disconnected the rear level sensors both sides cleaned them with WD40 and applied some grease, I then swapped them over to the other side and reconnected.

As soon as I switched on the ignition the air compressor kicked inn but the car went too high again.

So I tried to deflate with ista D nothing happened, so I disconnected compressor fuse and the air pipes from the compressor valve block let the pressure release all the way.

I then connected the pipes to the valve block, but the pipes won’t tighten as thread is made of plastic and it got damaged so I used the PTFE tape and then tightened them connected the fuse back on started the car, compressor kicked in and stopped at the correct height.

I then went on a ride came back home no warning on dash and no codes on ista d. Yayyyyy

However I’m still nervous to go on a long drive but I will take a courage and go will update tomorrow.