Nanocom to Diagnose Air Suspension Fault

to remove the plug give it some anti-rust spray and let it stay a bit

to inflate the bags, unplug the compressor and the air inlet valves, improvise a wiring as to connect the valves and the compressor all in parallel and give direct battery feed to them as to get voltage all at the same time(you can insert a 30A fuse on the wire just to make sure)

watch carefully the level and when it's at aproximately normal height cut the feed to not overinflate/blow the bags ...that's the "electric" method

...or you can source 2 pieces of 4mm pipe , insert them in push-in one way valves, pull out the original pipes and insert the "assy" into the bag's push fit connector...then you can use a compressor to inflate them and let them there untill you fix the system... something like these with a piece of pipe in them to fit into the bags (but these are too expensive for what they are) Air Suspension emergency Air Valves 4mm OD Discovery 2 | eBay

Thanks again sierrafery... never thought of using anti-rust spray on plastic connectors, but I'll give it a go..............

And I'm not sure I have enough knowledge to improvise the wiring you suggest, so maybe I should just stick to your second option.

But thanks again for your help.

frostymorning said:

Thanks again sierrafery... never thought of using anti-rust spray on plastic connectors, but I'll give it a go..............

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the anti-rust is for the corroded contacts(and these are metal)

I realise that now.... just didn't think something with that small a point of contact would fuse so tightly... i assumed the body was sticking.... But this is a big learning curve for me, so your help is appreciated.... and if you feel like giving a tutorial on how to set up the kind of parallel wiring you mentioned, that would be greatly appreciated too..... just don't want to send a jolt of current through something I shouldn't...........

in the scheme is how you have to connect the valves and the compressor together...this way if you give it voltage the valves will open and the compressor will pump the air in the bags...when you cut the feed the valves will close and if no leaks are present the air will stay in the bags for days ... you have to unplug everything there(especially the exhaust valve) and leave unplugged to make sure that the management will not give a deflation command while driving

in a nutshell ... based on the ride height sensor's inputs the ECU manages the air valves + the compressor to inflate and the air valves + the exhaust valve to deflate the bags.

I appreciate how the SLS is supposed to work sierrafery, it's just that my SLS seems to have forgotten....... And at the risk of exhausting your patience, just one last query... Would you recommend connecting the negative lead to the negative terminal of the battery or to the car body... or doesn't it make any difference?

Just thought I'd add my 2 pence worth

frostymorning said:

I appreciate how the SLS is supposed to work sierrafery, it's just that my SLS seems to have forgotten....... And at the risk of exhausting your patience, just one last query... Would you recommend connecting the negative lead to the negative terminal of the battery or to the car body... or doesn't it make any difference?

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as long as the battery is in situ connected it doesnt make any difference

I am also having problems - the compressor won't run.

When I try to lock the car I get a beep from the alarm suggesting one of the doors is open (all doors are closed!)

Is this maybe the reason the compressor won't run? I've also found out that connecting a battery directly to the compressor allows the system to pump up, so the system is OK, it's just not getting any power via the ignition

Is there an easy way to identify which door is giving problems?

deffinately if one of the door switches doesnt work(it acts like open) the compressor wont run... hop in the car, open the driver's window, reach out and lock with key(to not activate the volumetric alarm) then start opening doors/taildoor from inside(the bonnet switch has nothing to do with SLS)... if one door will not trigger the alarm that's the guilty one... if the alarm goes of when you open a door shut it off with the fob then lock back with key for next test.

By the way did you check FL9 and the SLS relay (R5) in the engine bay fusebox? ...cos the misslock could be given by the bonnet switch too

sierrafery said:

By the way did you check FL9 and the SLS relay (R5) in the engine bay fusebox? ...cos the misslock could be given by the bonnet switch too

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Thank you for the advice on how to check the doors!

Could you please give me a bit more detail over the bit I've quoted? (I have checked the 30A fuse for the compressor - it's OK, just didn't understand the other bits!)

R5 = SLS(self levelling suspension) compressor relay, you can swap it with R3(headlamp wash) for test... they are indicated inside the fusebox cover

i told you about these to make sure they are good cos the misslock warning could be generated by the bonnet switch aswell which doesnt affect the compressor

I think it must be one of the doors - the possibility to raise the suspension to the high position hasn't worked for a while.

Have already swapped relays to check

Belated Update

With advice from other threads in this forum I successfully replaced the height sensors and air suspension units at the weekend, so thanks to the posters concerned. it is however worthwhile making sure you have four new 10mm M5 flange hex bolts before you remove the old sensors. The bolts I pulled out had lost so much thread they looked more like rivets and wouldn't fit into the new sensors. It took me a few days to obtain new bolts.

With advice from sierrafery I cleaned up the plugs in the SLABS ECU and inflated the suspension units using a standalone compressor. Cleaning the plugs didn't seem to make any difference to the onboard system, but at least the vehicle is fully mobile again.... so thanks sierrafery.

This weekend it'll be time to investigate the compressor and valve block..........