Anyone changed one of these? I hear they are a bit of a pain to do and they need recalibrating?

My suspension is still 'randomly' dropping to the rubber stops. Thought I'd cured it with a replacement pump, but no luck. It was good for a day then dropped whilst I was parked up, engine off, and after a couple of minutes stationary.

To date I have:
Changed the pump unit with a new one to eliminate the pump and valbe block (no difference)
Cleaning all the connecting plugs going to the plugs
Raised the suspension and unplugged all connectors to verify ther airbags are both 'leak-free'.

Edited: both bags changed last year.

Only things left are the height sensors and slab ecu, unless I want to change all the wiring loom - I think not!

As an aside. I now have a brand new, used for 24hours suspension pump for sale if anyone needs one?

I'm sorry to inform you, but the most often problem with air suspension is ....... the air bags.
Be aware that they have an almost inbuilt "psychic" way of knowing when you're testing them so they stay inflated and only leak when your back is turned.
You might have "tested" the airbags, but the leaks can reseal and unseal at any time. I recommend that the bags be changed almost as a diagnostic measure before you even think of looking anywhere else.
Change the bags.

+1 for the bags. They don't even show up a leak when doing the soapy water test. How old are they? Most people say they're only good for 5/6 yrs.
Griff

I'm aware of the airbags being a problem....Nope, bags are good. Changed them last year.

It is possible, but unlikely the suspension will drop equally on both sides at a very quick rate if it was a simple airbag leak, though I'm more than happy to be proven wrong as that would be the cheaper/simpler solution.

They have been up now for another 24hrs (with all plugs disconnected) and I've driven to work and back. However, if I reconnect the power then it will drop again after 100m of test drive and the warning light comes on.

A mystery!

Oops, sorry - forgot about the search function. My brain is fried...

Bags are still up, no problems since Wednesday but that's with all the plugs at the pump disconnected - definitely not a leaking problem.

Has anyone had similar symptoms (as original post) caused by a single dodgy height sensor? I have one which is suspect (have ordered 2 replacements) but I wouldn't have guessed the suspension would drop so quickly, and equally, on both sides.
Maybe the compooter doesn't like a sensor being duff and shuts down as default with the warning light....
More investigation

Finally had all my order from JGS 4x4....
All seems to be working as normal again after 3 days of testing, and I appear to have a 'better' normal height driving level. It always seemed just a little too low and the suspension used to drop to the stops overnight.

Can't say I'm the oracle on this, of course, but through 'process of elimination' the fault on my suspension seems to have been causee by one dodgy height sensor. I replaced just the one I suspected might be at fault and magically all is well. No idea if I'm just lucky and it will be an intermittent fault, but so far so good.

To recap:
Disco suspension had dropped to the stops en route and the warning light came on- missus limped back home.
Tried a brand new pump (now for sale) but didn't solve the problem as it dropped after parking up after a test run.
After a couple of days I disconnected the battery, reconnected, started up and the suspension raised up. On Sieraferry advice I unplugged everything and ran it for a few days to check the airbags (replaced last year)
All good, but as soon as I reconnected all plugs at the pump it dropped again after a short run.

One sensor had been 'botched' at the mounting bolt, by me.......
Changed the sensor and all is well again.
Didn't have to recalibrate anything as I had raised the suspension to Max height ( to assist in fitting a new Watts linkage) and unplugged everything at the pump. All seems to have settled evenly so no issues yet.

Lesson for the day - sometimes a short cut McGyver solution is a long winded pain-in-the-arse.