ReGULT51

Hello - looking for any suggestions or ideas.

07 GL450 w/ 210k miles.Every part of the Airmatic has been changed out at least once during it's life. Arnott air shocks in all four corners.

Driver front suspension dropped to bumpstops. Psgr front looks similar but not as low. This has repeated itself not three times, with the last time being after we changed out the driver level sensor since the Autel Diagnostic was showing error 5130 ("check component B22/8 Left Front Level Sensor"). Switching this part for new didn't fix the problem. Rear does not drop. When the front drops, dashboard error of Suspension Malfunction displays and the vehicle will not respond to any suspension commands via dashboard. Clear out error codes on the Autel and the compressor kicks on, raises vehicle and it functions normally, until the problem resurfaces.

1st time suspension dropped - parked overnight in garage
2nd time - +7 days later, parked overnight in garage
3rd time - +4 days later parked overnight in garage
4th time - level sensor replaced, +4 days later, vehicles parked in garage, looked ok at 8am. Came back at 11am and suspension was dropped.

Since the air comp. does turn back on when the error code is cleared, we don't think that's the issue. Since left level sensor was replaced and issue repeated, don't think that's the issue. Thinking it may be a slow leak in the driver side airbag. Just not sure why it's so intermittent.

Any thoughts, ideas, directions to look at appreciated.

Thanks.

ReGULT51

Update:

Shop cleared the error codes and the compressor turned on and raised the vehicle to normal ride height. Shop also removed the new level sensor and reinstalled the original level sensor, since this didn't fix the issue. Parked in garage and I raised it to offload height. Measured ride height on front driver side, since that's where it drops. Visually and physical inspected air shock and performed soap test (no access to the backside of shock) but nothing seemed out of ordinary.

+1 day: measured ride height again and verified it hasn't changed. Visually, the other three corners look unchanged as well.

Looking at my records, I replaced the left and right air strut as a warranty replacement from Arnott at 166k miles two years ago. Around the same time & mileage, air compressor and pressure valve were also replaced. Current mileage is 209,800.

ReGULT51

So the GL has been parked for 2 days at the highest suspension (i.e. offroad height) setting. Reading through various threads regarding GL and related Airmatic issues, there could be a variety of causes. I'm wondering if I should cycle the compressor between normal and highest level to see how the compressor handles the load. I'm suspecting the compressor isn't the issue, though, as it works all the time AFTER the suspension malfunction is cleared.

Since the issue still occurred after replacing the driver side level sensor, i don't suspect that.

Valve block was replaced about 50k miles ago.

I guess it could be a leaking air shock, but wouldn't this be evident by now? Ever since I parked it, the height hasn't changed one bit, checking it regularly with a tape measure. I"m wondering if the suspension somehow "locks" in place at offroad height, not relying on the air shocks to maintain level? Doesn't sound like it should, but if it's a leaking air shock I would suspect to see some ride height sagging at this stage.

Could a faulty air compressor and/or relay be the cause, intermittently causing a "suspension malfunction" error through voltage spikes/drops even when not in use? But then this should be evident with some sort of error code related to the compressor, right?

Ideas and thoughts appreciated. Thanks.

DennisG01

I can't really help with the error code diagnosis part, but there is definitely no "locked in place" kind of thing. IF it's an airbag, and when they are "just starting" to fail, they won't leak at all settings. Sometimes the bag has to be folded/extended just right for the air to leak out... or, in other words, sometimes when the bag is folded just right it PREVENTS air from escaping. I would put it at the normal height and let it there for a few days, like you're doing now, to see if it leaks at that height. If it does, try the soapy water again (at any fitting you can get to, as well). You "might" be able to use a mirror or your cell phone to see the back side of the bag.

ReGULT51

Thanks! I was looking back at some earlier work orders and realized I had a similar issue two years ago, when I replaced the valve block, air comp. and front struts (in that order). The error codes was the same and what finally solved it was replacing the front struts. So, I'm building confidence that it's the air shock doing the behavior you just described, where there's a small leak somewhere.

I'm replacing the strut later this week and will update thread.

Max Blast

Has the level sensor wiring harness been checked and/or replaced? A shorted wire could be giving a false high level reading, causing the computer to dump the pressure in an attempt to level the car.

carlosrg

Has the actual lines been checked? I am kind of wondering if its the lines that have the leak themselves?

ReGULT51

Thanks for the ideas. As I left the GL in offroad height, I was able to notice a drop in the front driver side level, about an inch over one week. Looking more carefully over past records, I seemed to have a similar issue a couple years ago, when the suspension and valve block were replaced, to no avail. At that time, the fix was to replace the front air shocks (Arnott warrantied). So it appears that there's a small leak on the air shock. I just replaced the driver front shock with an Arnott warranty replacement and I suspect that will address the issue.

Now that it's parked, I've left it at regular ride height and noted the height for all four corners. I'm going to monitor over the next few days and see what happens.

I'll update it the issue persists.

abtabor6

Any updates!

ReGULT51

I received the warranty air shock from Arnott. That went in and the old one was returned to Arnott. So far so good - the car stays level and hasn’t sunk. It did come down about half inch on both sides in the front so I’m keeping an eye out on that.

i haven’t driven the car yet as I need to replace spark plugs and get t9 fixing the intak manifold lever arm, hopefully by simply popping it back in the socket and not having to remove the entire manifold.

Ill update id the replaced air shock doesn’t fix the issue.

ReGULT51

So far so good, The car has maintained regular ride height since installing the new driver front air shock. Interesting enough, it appears the height has lowered all around by about an inch, so I’m not sure if the malfunction forced the vehicle into an elevated level.

Working on manifold issue to get it past smog test...