Self Leveling Suspension InActive - Error code: Compressor Relay

[Frontman]

I posted my fix ages ago and still changed to rear springs. My only other bit of advice would be to check the control mod that sits down in the battery compartment. I always had to lift up the lpg tank to unhook the battery and noticed that the plastic moulded box that it sits in was wet in the bottom. I removed the battery and the box and found that the suspension control and dcm had been sitting in water.
You can pump each side up using a 9V battery to actuate each side. if the compressor is running it will not pump up unless one or both of the valves is open.
I managed to get both sides to the correct hight manually then unplug the unit or it will sink when parked or when tailgate is opened.

[dark_stranger]

[quote="Frontman"]
I posted my fix ages ago and still changed to rear springs. My only other bit of advice would be to check the control mod that sits down in the battery compartment. I always had to lift up the lpg tank to unhook the battery and noticed that the plastic moulded box that it sits in was wet in the bottom. I removed the battery and the box and found that the suspension control and dcm had been sitting in water.
You can pump each side up using a 9V battery to actuate each side. if the compressor is running it will not pump up unless one or both of the valves is open.
I managed to get both sides to the correct hight manually then unplug the unit or it will sink when parked or when tailgate is opened.
[/quote]

Andy on here sent me a spare control module to see if this was the issue and swapped out, but still not working.  The battery well is dry so not a water issue.

[dark_stranger]

Arrrrr got a replacement of the whole suspension unit found under the spare wheel, plugged it in and still the pump doesn't engage!!! Im going to plug in my scanner 1.4 to see if anything needs to be reset, but I guess apart from the sensors, what else is there?  is there a way to test the sensors, etc. manually.

[dark_stranger]

OK, slight progress, I found a thread where a guy was having similar issues and had figured out how to engage the compressor manually to fill the suspension air bags.  On the compressor there is a relay, he bypassed the relay as per below pics.  The pics where sourced from the thread...

http://www.xoutpost.com/bmw-sav-forums/x5-e53-forum/78613-air-suspension-manual-pump-up.html




This fired up the compressor, but when I checked the air pipes (red/blue) no air was coming out of them.  These pipes have to travel through solenoids (one for each pipe) and it would seem the air is not passing the solenoid.  I therefore looked at the solenoid and they contain a what I guess is magnetic valve that when sticking out stops the air, but when pushed in, allows the air to flow to the air bags.  I therefore taped up the values, bypassed the relay and was able to pump up the air bags.
 



This now opened up lots more questions, what controls the solenoids to open/close? the suspension sensors? if so, do the sensors work independently or together as the chances of them both going at the same time is unlikely, of if one is out, will it not work? .  The airbags, how much air are they meant to take? when full, are the firm to push in?  as I don't want to over\under inflate.

[jaynana]

It is the EHC CM and 13 from the pump, 11, 26 for blue/red from the diagram posted before.

U could try powering those manually, should open the valves.

If not the valves are busted. If they do open Id suspect the EHC CM.