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2008 GL450 with 50k miles.

Symptom of the problem -- Its right rear air spring is not getting inflated so that corner is sitting low. While I can raise and lower car and 3 other air springs are all inflated, right rear air bag is soft to the touch, with no pressure at all inside.

So far have checked the following:

Air bag -- no it doesn't leak. Uninstalled it from car and pressure tested with a compressor. No leak at air hose connector (at least not a large one to cause air bag no inflating at all. Sprayed soupy water didn't see bubble, but with no pressure fed to this air bag this test probably doesn't mean anything.)

Compressor -- It works fine. I can raise and lower car ok, except right rear corner is hanging lower (with no pressure in that air bag)

Valve block -- it's brand new. Took car to an independent mechanics, he said valve block is bad so replaced w a new one from dealer.

After replacing valve block car still behaves the same. The mechanics said he just needs to recalibrate level sensor but haven't got around to it yet.

Does this make any sense? With car raised, right rear corner is sitting 3 inches lower than rest (again this is with zero pressure in the right rear air bag). How could calibration be possibly off by that much?

I am starting to double if this guy knows what he is doing.... any thoughts and advice would be greatly appreciated!

Thank you.
 

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It may be a faulty level sensor at that location or an airline leak leading to that position. Since you already checked at the fitting I suspect it could be further back into the line.


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It may be a faulty level sensor at that location or an airline leak leading to that position. Since you already checked at the fitting I suspect it could be further back into the line.
James, thank you for the reply.

If there is a leak further upstream, I guess it is a large one and easy to spot since the problem air bag is getting zero pressure. Given the car is holding its height with compressor not running (granted with right rear corner lower), is it possible for some reason (safe maybe?) the computer disabled the vale distributing pressure to right rear and it has to be reset?

If the mechanics manually connects 12 volt to the pins corresponding to "HR" port on the valve block, should he be able to override the computer controls and force right rear bag to inflate?
 

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Hooked up to star diagnostics you should be able to force it to rise, however if there is a leak then as stated that will not work. That’s a pretty long air line so they make a repair kit that allows you to splice the original air line with a shorter length air line.


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Discussion Starter #6
If the mechanics doesn't have Star diagnostics software, can you test it manually by disconnecting HR hose at valve block, start the car and see if air is blowing of of HR port? Or blowing compressed air into the hose corresponding to HR port and see if right rear air bag would inflate?
 
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james.calton1
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