BMW E70 Rear axle Air suspension

[Alan Gunn]

Some years ago now when i changed one on my 2002 x5 i didn't know any better and got a low cost one from ebay or Amazon and it is still working now.
It was 8 or 9 years ago.

[Greydog]

Well after using just about every source for information I can find or think of I am wondering why something so simple have to become so damn complicated ?? Through an ex- neighbour who works for BMW I have a 200+ page document on Advanced Diagnostics using ISTA and ICOM, today I should recieve my new EHC. So the plan is fit and calibrate the the New EHC (a simple process using ISTA) if that doesn't do it from what I have read there could be an issue with the Bus system between the EHC the FRM and JBE. This could be a resistance issue caused by a failing termination resistor or as daft as a poor earth point or corrosion in one of the Bus splices.
Then there is always Springs I am beginning to understand why so many X5's and RR end up on springs instead of air

[Leslie]

Don't give up bud you have got this stick it on see what the reading is , if its still -127 it ain't that and no calibrating will sort it .

[Greydog]

Thanks for the support Leslie
Well it wasn't that EHC made no difference !!!!! So back to reading and learning about BMW Bus Systems and it is an eye opener for me to say the least. So how many Bus systems are operating in an E70 ? Ten, D-can, K-can, PT-can, F-can, Flexray and Most then in the back ground Lin-Bus K-Bus BSD and Lo-can
The MOST system I can ignore at the moment as that deals with Information systems Communication and Entertainment So I need to concentrate on the Flexray, (Star System) F-can and K-can (are Linear 2 wire systems) Flexray links the suspension EHC and sensors to the Vertical Dynamics Management Flexray is linked to the rest of the car by K-can and F-can once I get my head around the architecture and how to measure each systems noise levels I may be able to separate them and isolate the culprit. Thought I had given this up when I retired

[Leslie]

what does the right rear read when you unplug it ?
Are you sure the lines to the compressor are refitted correctly incase its pumping the wrong side ?

[Greydog]

Morning Leslie
Unplug the sensor and get Suspension Inactive on the screen and dash plus fault code 059F if I recall correctly
As I read/learn more about the way BMW configure the Bus architecture I am leaning towards a fault/failure some where in either the K-bus or F-bus. It is possible that a Termination resistor has started to fail I hope that isn't the case as apparently they are located on the PCB inside end of line Control units. As I am not seeing other faults and from what I am reading the K-bus will still communicate on one line just at reduced capacity and speed either side of the damaged area. So todays fun task is to try and locate all K-bus splices close to the Flexray connections. Then go digging in the loom to find them.

[Leslie]

Are there any earths at the bottom of the rear fusebox or in the bootfloor ? , I still think/hope it will turn out to be something simple