Chassis System failure nightmare
08-04-2019, 08:05 PM
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Chassis System failure nightmare
Warning: long and depressing and if you don't have PIWIS or PASM experience don't waste your time
My wife has a 2011 Cayenne TT that has given us random "chassis system failure" notifications over the last year, but no actual symptoms other than being locked out of the higher levels. We never came out to a bottomed out broke airbag (until recently.) A few searches suggest I replace the valve block. So I did. That gave us more often chassis system failures. Then after asking the local DFW Group for a recommendation on where to take it, she went to Mayo Performance to have them hook up the PIWIS and give her a diagnosis. All they did was get the trouble code, same code Durametric had, 000284 ("I'm too low and can't get up"). They provided no other diagnostic other than suggesting they randomly start replacing airbags at $1500/corner. This is pretty disappointing and makes me suspicious of indy shops. They had full access to live data with the PIWIS, plus activations to see if they system would respond, but instead took my money read one code and sent her home.
About two days after our visit to Mayo Performance we came out to a Cayenne sitting bottomed out on a front bag. I moved it to my home shop and tried to start diagnosing stuff on my own. If I disconnected the battery and reconnected it the compressor would come on sporadically. I bought a new isarscan tool. I believe the v960 model. It does live data and seems to pull errors that the Durametric will not. I got a compressor overheat error, so we replaced the compressor. The first day the compressor turned on and pumped the system up from 3 bar to 6 bar of pressure (I can see live data), but it never tried to raise the car at all. I also noticed on the live data that three corners are at ~2.6bar and one corner is at 12.5bar of pressure. This can't be right, but so far I can't find where the pressure sensor for each strut is. The v960 will show live data, but it will not do activations.
So I ordered another scan tool, this one is a Launch X431 Pro Mini. It's a little tablet with a bluetooth OBD2 dongle. Pretty cool. It does activations, or at least it says it does. I tried using the raise vehicle activation, that immediately sets a chassis system failure warning and displays an error code of "service mode not completed" This cannot be reset by the tool, but seems to go away with a key cycle. The system doesn't do ANYTHING NOW. The system pressure is at less than 3 bar, but the system never even requests it to turn on. It has given up even more than me.
So anyway, back to manual diagnosis. I realized there are check valves at each strut, so I pull the line and used shop air to fill the front bags. They hold air for about 15 seconds...so that sucks. I've ordered four new air bags, but I don't even know if I can install them without the car murdering them when I lower it to the ground. For now I guess my plan is to install the new bags when they come in and manually fill each corner with shop air in an effort to keep the new bags from creasing/ripping.
If you have any helpful tips of hints I'm all ears.
Aaron
My wife has a 2011 Cayenne TT that has given us random "chassis system failure" notifications over the last year, but no actual symptoms other than being locked out of the higher levels. We never came out to a bottomed out broke airbag (until recently.) A few searches suggest I replace the valve block. So I did. That gave us more often chassis system failures. Then after asking the local DFW Group for a recommendation on where to take it, she went to Mayo Performance to have them hook up the PIWIS and give her a diagnosis. All they did was get the trouble code, same code Durametric had, 000284 ("I'm too low and can't get up"). They provided no other diagnostic other than suggesting they randomly start replacing airbags at $1500/corner. This is pretty disappointing and makes me suspicious of indy shops. They had full access to live data with the PIWIS, plus activations to see if they system would respond, but instead took my money read one code and sent her home.
About two days after our visit to Mayo Performance we came out to a Cayenne sitting bottomed out on a front bag. I moved it to my home shop and tried to start diagnosing stuff on my own. If I disconnected the battery and reconnected it the compressor would come on sporadically. I bought a new isarscan tool. I believe the v960 model. It does live data and seems to pull errors that the Durametric will not. I got a compressor overheat error, so we replaced the compressor. The first day the compressor turned on and pumped the system up from 3 bar to 6 bar of pressure (I can see live data), but it never tried to raise the car at all. I also noticed on the live data that three corners are at ~2.6bar and one corner is at 12.5bar of pressure. This can't be right, but so far I can't find where the pressure sensor for each strut is. The v960 will show live data, but it will not do activations.
So I ordered another scan tool, this one is a Launch X431 Pro Mini. It's a little tablet with a bluetooth OBD2 dongle. Pretty cool. It does activations, or at least it says it does. I tried using the raise vehicle activation, that immediately sets a chassis system failure warning and displays an error code of "service mode not completed" This cannot be reset by the tool, but seems to go away with a key cycle. The system doesn't do ANYTHING NOW. The system pressure is at less than 3 bar, but the system never even requests it to turn on. It has given up even more than me.
So anyway, back to manual diagnosis. I realized there are check valves at each strut, so I pull the line and used shop air to fill the front bags. They hold air for about 15 seconds...so that sucks. I've ordered four new air bags, but I don't even know if I can install them without the car murdering them when I lower it to the ground. For now I guess my plan is to install the new bags when they come in and manually fill each corner with shop air in an effort to keep the new bags from creasing/ripping.
If you have any helpful tips of hints I'm all ears.
Aaron
08-04-2019, 09:30 PM
#2
Maybe the new compressor needs to be programmed and that's why it's setting the "service mode not completed."
I accidentally rest my parking brake settings and it wouldn't function until it was programmed again. Luckily, I had access to another cayenne and was able to get the code off of it.
I accidentally rest my parking brake settings and it wouldn't function until it was programmed again. Luckily, I had access to another cayenne and was able to get the code off of it.
08-04-2019, 10:58 PM
#3
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Aaron, do you have AllDataDIY? I seem to recall the airspring replacement procedure involving pre-filling each airspring before installing the strut and airspring on the vehicle.
Was the compressor you bought from Porsche? Or aftermarket?
And do you have AllDataDIY? There is a rather complex procedure to refill the system after opening it for any reason. If you just expected the compressor to pump the airbags up and lift the car - that's unlikely without prefilling it. The system isn't designed to draw in outside air. It's pressurized with nitrogen from a gas bottle - and the airbags must be prefilled BEFORE the vehicle is put on the ground and moved. There are specific warnings about how you will damage the airbags if you don't do this.
It sounds from what you've described as if you don't have any documentation on working on the system. I think obtaining that might go a long way toward resolving your problems, perhaps without replacing all 4 airbags.
Was the compressor you bought from Porsche? Or aftermarket?
And do you have AllDataDIY? There is a rather complex procedure to refill the system after opening it for any reason. If you just expected the compressor to pump the airbags up and lift the car - that's unlikely without prefilling it. The system isn't designed to draw in outside air. It's pressurized with nitrogen from a gas bottle - and the airbags must be prefilled BEFORE the vehicle is put on the ground and moved. There are specific warnings about how you will damage the airbags if you don't do this.
It sounds from what you've described as if you don't have any documentation on working on the system. I think obtaining that might go a long way toward resolving your problems, perhaps without replacing all 4 airbags.
08-05-2019, 10:33 PM
#6
Drifting
08-07-2019, 11:10 AM
#7
Aaron, if you don't have any nitrogen, swing over and grab my bottle of it.