UKC

Hoping someone can help

It seems that there is something wrong with the suspensiin on my BMW 3 series it's displaying "suspension autolevelling failure" and I've been quoted £1000+ for a new compressor relay and hose. However I'm not convinced the garage has done any fault finding, is there a way I can check whether there is actually a problem with the compressor or if it's tripping out because a hose or bladder has a problem?

In reply to balmybaldwin:

Needs first to run a diagnostic and see what it's pointing to, if it's the compressor you then need to check it's getting feeds and earth if it's a simple 12v unit but if it's operated of CAN/LIN it's a little bit harder. Something you can easily do at home is to just disconnect one of the struts and feel for compressed air out of the pipe from the compressor. The connections are normally like the JG plumbing connections but much smaller. Don't forget to check simple stuff like the fuses aswell

In reply to balmybaldwin:

My guess would be it's just a 12v compressor no different to what you would use to pump up your tyres except it's plumbed in to your suspension, normally on the rear of estate cars. But BMW being German they could have over complicated things and made the compressor only switch on when the cars ECU
tells it to over the cars CANBUS network (or if it's new they now use flex ray) so makes it harder as the compressor may be fine but it's not getting a signal from somewhere else to tell it to start working

I am getting the information of a mate of mine

In reply to john_mx:

It's an oft stated myth that equals over-complication. Lower end (1 & 3 series, maybe 5) BMWs are no more complicated than other cars in general, and in my limited experience are actually simpler. That said, mine doesn't have autolevelling thankfully so maybe this is a particular headache.

Barmy: BMW forums are well worth a trawl.

In reply to balmybaldwin:

Thanks for that, will get it to a proper diagnostics machine in the morning then

In reply to balmybaldwin:

See if you can find someone with a copy of INPA installed on their laptop and a cable to plug into your car. You can buy it yourself from ebay from around £40 and then do your own diagnostics, but it's not the most intuitive bits of software to use, and it needs to run on Win XP or VM.

Not your specific car, but might be similar?

http://www.bimmerforums.co.uk/forum/f15/2005-530d-e61-touring-self-leveling...

As mentioned above, the BMW forums would be a good place to start your own research.

In reply to john_mx:


As an avid fan of Wheeler Dealers you are almost certainly correct, but upon the donning of orange gloves and liberal use with a multi-metre, the offending part is almost certainly cheap and easily fixed... once you have found out what the issue is. Any internal network will receive the signal and no doubt click a relay that operates a simple motor of some sort.

In reply to balmybaldwin:

Without the BMW maintainance/fault-finding manual I suspect you'll find it very hard to differentiate between the various possible failures that would be detectable by the ECU.

It's possible the computer is reporting a failure to respond to leveling commands. Could be a failure to change height or a failure to detect changes in height.

It's also possible the computer is detecting a parameter out or range, too much/little current to the pump or a valve, a pressure sensor out of limits, a blown fuse...

First step for a DiY fix is understanding what the system does, where all the bits are and having a read around to see if there are known issues.

It could be something as simple as a cracked coil spring or flat tyre meaning the autoleveler can't level the car despite working properly.

If it were mine as a BMW fan and electronic engineer who enjoys tinkering with cars I'd pull my hair out then hope it somehow burned to the ground while properly insured Bloody over complicated modern cars! Failing a lucky lightning strike frying it I'd try another garage, ideally a BMW specialist with a recently trained ex-BWM technician on staff.

jk

In reply to jkarran:


Hence my suggestion of INPA. The BMW fault codes are actually very good at pinpointing errors, they have much much more detail than a normal 'fault code reader' from ebay will display. You just need a suitable piece of software (like INPA or DIS etc) to examine the data.

Agree with your suggestion of finding another BMW indy gargage, or burning it. (joke!)

In reply to balmybaldwin:
Ok, so it's confirmed that the compressor is screwed. It was sitting in a bath of water. (not literally - but it was dripping wet)

So I need a new compressor, but more importantly I need to find where the water is getting in to stop the new one being buggered.... Will start with looking at the boot seal first, but if anyone knows of a common failure (it's about 9 yrs old 62K) I'd be glad to be pointed in a different direction