BMW E70 Rear axle Air suspension

Alan Gunn · Post by **Alan Gunn** » Wed Oct 07, 2026 6:04 am

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 · Post by **Greydog** » Thu Oct 08, 2026 8:26 am

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 · Post by **Leslie** » Thu Oct 08, 2026 3:56 pm

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 · Post by **Greydog** » Thu Oct 08, 2026 5:53 pm

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 · Post by **Leslie** » Thu Oct 08, 2026 6:56 pm

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 ?

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