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Discussion Starter #1
got the dreaded suspension inactive message today so took the car to the local diagnostics center and they came up with this message,"resevoir pressure static when reservoir is inactive", what does it mean exactly and whats the cure, they tried to reset it but it didn't want to know, now it just stays at ride height :(
 

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Hmm, I've never seen that one before. If it is saying reservoir pressure static, that could mean several things, but I'd say the most likely scenarios are:

  • Failing compressor[/*:m:3nllpgjr]
  • Bad pressure switch[/*:m:3nllpgjr]
  • Low battery causing faulty readings[/*:m:3nllpgjr]
Checking all the electrical connections to make sure they are all clean/secure might not be a bad idea either.
 

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I thought I had typed a reply to this already ... maybe not. A lot of this is speculation on my part of messing around with the EAS and the errors you get.

First and foremost, did the garage reset the errors in the (EAS) air suspension system AND the errors stored in the headlight ECU as well. Yes, if you dont reset the headlight ECU, then the EAS errors wont clear properly either. What happens is that the headlight ECU listens to the rest of the car and logs any errors they generate in its own memory. Even if the other systems reset and clear ( which the EAS does ) on start up, the car will go round all the ECU's and ask for the errors. The EAS says I'm OK, but the headlight ECU replies with the previously stored error, and so the car thinks that the EAS has a problem ... the error then seems to get re-logged back into the EAS ECU ... thus the fault doesn't go away.

Secondly, the error of pressure static: Right, as I understand it, the error stems from the system not thinking that the sensor that measures the tank pressure is working correctly. In order to check it, what the system seems to do is that when you start the car, it will run the compressor pump for a couple of seconds, and checks whether the pressure in the tank rises accordingly. If it doesn't, then it assumes the pressure sensor is not working, so logs the error in the ECU. This type of error is a soft error, so the next time the car starts, it will repeat the test. Also, even when its working OK - the time to test the pump seems very short. I've watched the pressure rise as you run the pump, and the reading doesn't really change that quickly. So i think that sometimes the pump isn't run for long enough to allow the pressure to read a different value. Its too quick to log the error I think.

However ... remember what I said about the headlight ECU?

Its logged the error ... so when the car starts, the EAS tries the test again ... however, halfway through, the headlight ECU tells the car that the EAS has a problem .... the EAS thinks "oh - i've got a problem", and stops the test ... so it never gets the chance to reset of its own accord.


I have replaced the sensor ... but it didn't seem to make much difference ... the error came back very quickly after replacing it. I may give it another shot though , just in case I got a bad replacement sensor.

Beyond that, I have another couple of ideas:

1) Investigate whether I can disconnect the headlight ECU so that it stops listening to the errors and false logging them.
2) Some sort of simple circuit across the terminals of the pressure sensor, so that at start up, the voltage is always rising during the time that system is reading the sensor. I was thinking of a capacitor ... so that it'll always start at 0V initially on start up, then rise up to the real voltage over a few seconds. That way, the ECU will see a rising voltage when the car starts, but the real reading wont be affected as the capacitor will follow the real voltage ( just with a few seconds delay )
 

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Discussion Starter #4
i ended up taking it to a main dealer who cleared the fault codes and did a software update aswell, this cured everything and is running fine now
 

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did they say what the software update did and can I ask how much it cost?
 

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Discussion Starter #6
he said something about that it changes the temperature range of the pump sensors and some other things, according to him the car hadnt been on a computer since 2005, we've only had it 18 months, it only cost us 30 euros to wipe the fault codes and do the update
 
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