XSeries-forum

Hi, me again. Sorted out the lumpy idle problem then almost instantly the "self levelling inact" came up the back end dropped to what I would say is its lowest point. Had a root round and took the relay cover off the compressor unit and pumped the back end up by holding the contact on the relay. So it's not the compressor or airbags/ leaks. The only bits left to check are the ride height sensors and the plug in control unit as I think the compressor is lacking a signal to start up.
Does anyone know where the plug in control unit is.

Cheers Col

Search on here for self levellign susp inact - there have been huge amount of discussions, quite often battery related. Have you had the battery out recently? How old is it? Have you charged it fully? If you've been solving a lumpy idle problem then maybe you've been cranking it a lot?

New battery so hopefully not the issue, the car took around 5 mins to start to lift so I'm thinking that the compressor needs looking at, and as it drops there must be a leak so am now thinking of putting springs on and doing away with the problem altogether.
Thank you for the reply

col

Mine was a broken wire in the loom between the controller and the front ride height sensors. It had me beat and my local indie found and fixed it.

So how does a high end car company think that putting the battery in a plastic box ( with no drain holes) and then adding some electronic control units was a good idea.
The control unit for the rear air suspension is located in the box slung under the boot.
Removed the three battery struts and then the two screws for the plastic cover ( with BMW on) lifted the cover to find 3" of water in the compartment. Lifted the module holder out and found the suspension and PDC control units resting in water.
I was amazed that the units were not sealed but it did allow me to check the damage.
Bottom line is that the air suspension unit is knackered and contacts on one of the PDC unit plugs is wet and slimy.

So I have found my air sus problem (the PDC ) can wait for another day. And it looks like spring time ( no not the weather)

BUT what would happen if you were stuck with the suspension on its ass.... There IS a fix, as long as you have no air leaks.
Access the compressor unit,
Remove the cover ( orange in my case ) from the relay
Get a 9 volt (PP3) battery
There are three solenoids on the unit, we are looking for the two together, one has a blue and one has a red pipe.
Attach two wires to the 9 volt battery
Where the two wires go into each solenoid to can see the top of each terminal in the plug
Try both wires from the 9 volt battery on each terminal. If it clicks that is the one
You can press the contacts together( with your fingers) on the relay
The solenoid ( red left, blue right ) will allow the air into that side then change to the other side until the car is at the desired hight,
If your compressor is ok, one side of the car will start lifting within 30 seconds ( from zero air)
Unplug your control unit and you will see if you have a leak in the system or the unit/ sensors are KOd
Or you could let the air out of both sides and charge the local kids for a ride round the block over a few speed bumps.

BMW put it in plastic so there is no risk of acid damage.  The battery is vented externally so there should be no issue.

If you have water in that area then you need to start looking at window seals, roof seals & drains, rear door seals as that is the most likely site of the leak.  There should not be any water in that compartment, hence no draining needed.

BMW try to get a 50:50 weight split over each axle which is another reason things are in odd places.

Several people have had leaks in that area before.......and well done with the 'fix'.

Richard

[quote="Frontman"]
So how does a high end car company think that putting the battery in a plastic box ( with no drain holes) and then adding some electronic control units was a good idea.
The control unit for the rear air suspension is located in the box slung under the boot.
Removed the three battery struts and then the two screws for the plastic cover ( with BMW on) lifted the cover to find 3" of water in the compartment. Lifted the module holder out and found the suspension and PDC control units resting in water.
I was amazed that the units were not sealed but it did allow me to check the damage.
Bottom line is that the air suspension unit is knackered and contacts on one of the PDC unit plugs is wet and slimy.

So I have found my air sus problem (the PDC ) can wait for another day. And it looks like spring time ( no not the weather)

BUT what would happen if you were stuck with the suspension on its ass.... There IS a fix, as long as you have no air leaks.
Access the compressor unit,
Remove the cover ( orange in my case ) from the relay
Get a 9 volt (PP3) battery
There are three solenoids on the unit, we are looking for the two together, one has a blue and one has a red pipe.
Attach two wires to the 9 volt battery
Where the two wires go into each solenoid to can see the top of each terminal in the plug
Try both wires from the 9 volt battery on each terminal. If it clicks that is the one
You can press the contacts together( with your fingers) on the relay
The solenoid ( red left, blue right ) will allow the air into that side then change to the other side until the car is at the desired hight,
If your compressor is ok, one side of the car will start lifting within 30 seconds ( from zero air)
Unplug your control unit and you will see if you have a leak in the system or the unit/ sensors are KOd
Or you could let the air out of both sides and charge the local kids for a ride round the block over a few speed bumps.
[/quote]

im removing the air suspension from mine.
The air bags split so ive fitted springs.
If you need the control box drop me a message It all works but I was not spending the money on new bags when springs are the better option