Air sus workings

marinaman · Post by **marinaman** » Sat Mar 18, 2017 5:03 pm

Hi
Just wondered if someone can explain this one, the car is a diesel sport 04 reg, in the rear is the air compressor, this works as i applied 12v. The car seems to be at the correct level and does not sit low. I have no dash switch for suspension. The module in the boot which i think should be at the side of the parking sensor one is missing, just a multiplug hanging there.
So i think i may have the version that self levels when needed. Cant work it out as a newbie to BMWs, i dont want to buy a module if it will do nothing but wonder why its missing or are some cars not using the air supply even though its fitted.

Horizon · Post by **Horizon** » Sat Mar 18, 2017 5:31 pm

Post a photo, that spare plug in the boot is to plug the towbar electrics into

Alan Gunn · Post by **Alan Gunn** » Sat Mar 18, 2017 5:48 pm

New to the x5 myself and have a 52 plate 3.0d sport as well.
My air suspension does it's own thing i think.
I notice it when i park on an angle/slope and get out i can hear it working.
Well i think i can lol.

X5Sport · Post by **X5Sport** » Sat Mar 18, 2017 6:26 pm

3.0d Sport was fitted with self-levelling rear air only. No adjustment controls as the level is determined by the load in the boot or passenger compartment. There are two level switches, one per axle that work out how much pressure is needed in the rear airbags.

You could specify full air at build, and that gave you the height control.

marinaman · Post by **marinaman** » Sat Mar 18, 2017 6:33 pm

So where does the module for the self levelling live ? i suppose i could test by putting the family in the boot could i ?

Horizon · Post by **Horizon** » Sat Mar 18, 2017 6:38 pm

[quote="marinaman"]
So where does the module for the self levelling live ? i suppose i could test by putting the family in the boot could i ?
[/quote]
If the module is removed it lights up the dash like a Christmas tree, as it doesn't just control the air suspension. As I remember Raj removing it when he removed his air suspension air bags and fitted coilover, he removed the module and had to put it back in as it was shared with other functions.
Stop looking and enjoy your car

X5Sport · Post by **X5Sport** » Sat Mar 18, 2017 7:00 pm

Why are you looking for the module? If the system works then leave well alone. Self-levelling suspension has no user controls and is driven by the sensors so there is nothing for the driver to do. Non sport variants (those with 17" wheels instead of 19") have coil springs all round with no air.

4.6/4.8 versions got full air.

There are gaps at the back for aux heating, trailer, different audio, TV depending upon build options. You will also find multiplugs besides the seats for the power adjust option. E53s were made with a standard and it appears all encompassing loom, unlike current versions which only get what is needed.

marinaman · Post by **marinaman** » Sun Mar 19, 2017 9:30 am

I was trying to find out if it was working, then i saw the loose multiplug next to pdc sensor, the chap i got it from told me if i found any problems to let him know and he would sort hence me trying to test things i didnt know about before. im just one of those. if its fitted i like to know it works types so i test everything as best i can, if i then get some cash back to fix any problems im in pocket.

X5Sport · Post by **X5Sport** » Sun Mar 19, 2017 12:52 pm

If it wasn't working then your rear suspension would collapse.

There is an online version of the BMW Service manual that might help you locate it. I can't remember the search you need to use though. You can also source a copy from fleabay pretty cheaply. Should help you locate everything

X5-D-Sport · Post by **X5-D-Sport** » Sun Mar 19, 2017 1:56 pm

As X5 Sport says...

If you develop any faults on the rear air suspension, the rear end, or one corner will sink...
It is TOTALLY obvious when one corner has sunk 7 inches & the wheel is sunk
into the wheel arch well.

As the man says, LEAVE this system well alone unless the rear end sinks. You can actually do damage to it by tinkering if you are unsure of exactly what you are doing.

Best wishes
Grant B

marinaman · Post by **marinaman** » Sun Mar 19, 2017 4:45 pm

Message recieved and understood, i take it then that if i load the car up in the rear it should kick into life ? just never such refinements before and like to know how it all works, i had the warning come on the dash after i changed the battery that active suspension was inoperative. i did some research and seemed a common thing but its still on the check control at each start up, car is not low at all, no hissing or sounds of the compressor working and rides very well.

X5Sport · Post by **X5Sport** » Sun Mar 19, 2017 5:53 pm

Should do. The compressor is inside a dome lined with thick foam making it hard to hear.

A couple of bags of sand - or a trip to IKEA - will load the systems and should trigger a reaction.

It will only operate if the two level sensors detect a change.

The warning is very common and most frequently a false one. If it is a genuine issue then you will get a re-trigger every time, and not just during start-up, and irregularly whilst driving.

It is typically triggered by a low battery, or by not waiting a few moments between turning the engine from lights on to cranking. Good practice with these cars is to allow the warning lights to cycle before cranking. It allows all of the on board systems to wake up and system checks to complete before the voltage drops during start.

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Air sus workings

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