w221 rear suspension colapsed

Botus

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drove off everything normal, 1/2 mile later gently going over smoothish speed bump could feel rear was wrong, got out.... completely bottomed out no air at all, front normal...

drove home slowly, parked on slightly uneven drive: diagnostics

5286 recovery times during bleeding of air suspension too long
LF sensor Signal 1 of B22/8 2.67 V, height 13 mm
RF sensor Signal 1 of B22/9 2.37 V, height -1 mm
Rear sensor Signal 1 of B22/3 0.49 V, height 127 mm

initially
compressor locked due to switch on time NO
compressor locked due to on-board network NO

but later
compressor locked due to switch on time NO
compressor locked due to on-board network YES

I never / can't hear the pump run today, the 40 amp fuses in the front SAM are OK. Relay and pump still in warranty. If the rear level sensors broken I'd be frustrated its got no corrosion round the back and I regularly lubricate it. But 127mm when its flat on the floor sounds like its related... Can I fig it with a screw driver get the pump to pick it up... pull the fuse and drive to get it sorted... if so which fuse I think theirs 3, 40 amps and I know its one of them

my diagnostics can't tell the pump to run... which is madening
 

bembo449

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jack it up , get underneath and have a look at what LK suggested , if the link bar to the height sensor has snapped off the back end wont stay up , its not an expensive part either
 

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The clamp on the rear anti roll bar for level rod has rusted and snapped. Only a few quid but a pita to fit.
 
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Botus

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thanks for support.... exactly at you say.

the spring clip on the lower ball fitting to the antiroll bar broke.... with enough left I have fixed with a jubilee clip as temporary bodge.... its got the car pumped up and a new (20 quid kit) from from MB grangemouth on its way

This clip is not fit for purpose nor safe... and then they go and fit the handbrake mechanism beneath it.... why isn't the sensor on the side where there's room?

I'm disgusted about this. From a safety perspective I would have all the individuals (who both designed, signed off and wrote the software regarding this suspension, locked up (for attempted manslaughter). It is of a wholly inadequate size and strength for the job. To compound this fault with software that says OK the sensor reading is missing, let all the air out and collapse the rear of the car as quickly as possible is just criminal... making VW emission drivability fix reaction ludicrous. If I'm in Germany doing 120mph round a tight autobahn bend is dumping the rear suspension down on the floor in seconds a good idea? I don't think so.
 
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LostKiwi

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To compound this fault with software that says OK the sensor reading is missing, let all the air out and collapse the rear of the car as quickly as possible is just criminal... making VW emission drivability fix reaction ludicrous. If I'm in Germany doing 120mph round a tight autobahn bend is dumping the rear suspension down on the floor in seconds a good idea? I don't think so.
That's not the logic.
The sensor says height is at +127mm so lower it (as you'd expect). The height doesn't change so it says lower it more eventually getting to the point it can lower it no more simply because the sensor is sill in the highest position as it's no longer connected to the suspension. At no time did it say the sensor was faulty and dump it to the ground.
It only figured out there was an issue after it had done everything it could to fix the suspension height.
 
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Botus

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the sensor sees continuously varying data, when the rod detaches the reading become stable. Therefore the software should say that's' odd do nothing until I start to see sensible data again,

if we are pedantic and don't like that it could say oh we seem a bit high let out a small % till I see it drops, that's odd no change, until I'm sure the data is real and varying as expected wait a bit then let out another small amount... if no change stop letting air out there's something wrong

dangerous stupid and incompetent
 

LostKiwi

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the sensor sees continuously varying data, when the rod detaches the reading become stable. Therefore the software should say that's' odd do nothing until I start to see sensible data again,

if we are pedantic and don't like that it could say oh we seem a bit high let out a small % till I see it drops, that's odd no change, until I'm sure the data is real and varying as expected wait a bit then let out another small amount... if no change stop letting air out there's something wrong

dangerous stupid and incompetent
You're dealing with an analogue system with simple electronics. Simple = cheap and less prone to software glitches.
If there is a failure of design it's only in using a material that isn't more resistant to corrosion.
 


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