wsmcycle

Error message said "vehicle too low". I pressed the raise ride height switch and it began to rise. I continued driving and the rear end began to bounce extremely, nearly off the ground. I crept back home. I tried again the next morning and the rear end of the car was still way high. I used the switch to lower it but it would not go down (though it said it was lowering). finally, the airmatic indicator came on. The rear was still high. Would someone please advise me what to do besides go to the dealer.

starbound01

The fact the vehicle rose tells you the compressor is good. The fact that you go the message tells you the sensor is correctly recording the *too low* condition; but that means nothing reagaring shutting off the system as the vehcile raises. The failure to lower leads me to think the distribution block has failed in some way. How many miles on the vehcile and have the airspings been replaced? Do yourself a favor and spend the $20 for a new relay before that causes your compressor to fail.

While this is subjective.... The only time the vehicle normally needs to actively adjust the height is highway/street transitions or manual height change. My opinion is we see these issues as a result of leaking airsprings. I think it goes down like this... the spings start leaking. The vehicle begins the process of compensating which is completely transparent to the owner. This causes the compressor to cycle frequently (its not designed to do that) which in turn makes the relay work freequently and eventually causes the relay to fail or stick. That leads to a burned up compressor. The frequent running of the compressor causes the compressor to exceed its capacity to dry the air pushed into the airsystem. The first object in the queue is the distribution block. The small amount of hot moisture condenses and the process of rusting the block or failing it's internal components begins. When this happens the vehicle start failing to fill or lower the corner(s). MB has failed owners in the programming design by not providing cycle count data warnings. How hard would it be to put up a warning that saying in the last x minutes your compressor has run y times.

When I think back to 5-12 months before the compressor failed, I can recall things like "hearing the compressor running" when pulling into the garage. The big *whoosh* shortly after shutting of the vehicle. Had I paid attention to those things i would likely have not had to replace the compressor. BTW, if you do get a new compressor, the parts guy will TELL you to replace the relay with the new compressor.

If you take the vehicle to MB the distribution block will be the first thing they tell you that is wrong. When that is done and the car continues to fail they tell you the airsprings are bad.

wsmcycle

spend the $20 for a new relay< where is this relay and do you know a part number? Generic?

I dont think the bags are leaking because the *** is still up in the air the 24 hours later.

Does that figure in to your conjecture?
Thanks

starbound01

The airmatic relay is green. Ask the MB parts guy for it - he will have them. The relay is in the main fuse box under the hood (left side). There will be a longer row of relays; 2 green and the rest white. The far left relay on the end is the starter relay. 2 relays to the right is the green arimatic relay. The new relay looks slighly different but it will be green. Pull the old one out, put the new one in.

There is no definitive way to assess if the airbag is leaking until the vehicle falls down. The bladder develops pinholes from dirt/sand abrasion between the seat and the rubber bladder. There are lots of threads where people have had the vehicle fall, then pump up and stay that way for a long time, and then later fall again. If I recall right, our right front fell, inflated and stayed that way for several days before it fell again (about 58K miles - both replaced under warranty). It all depends on if the seat is sealing the leak or if the join is sealed by the change in height. The vehicle is heavy and offers a lot of sealing pressure for a tiny leak.

My opinion was based on the rest of the information. I think your distribution block is the problem but I think you will find shortly you replace it, you will be replacing the airspring. Airspring life from MB sesems to be around 60K miles. We went about 80+ on the rear and i saw a thread once where someone had the problem at 40K. This is a wearable component much like a shock absorber.

wsmcycle

Thanks for the help
I will get a new relay and replace it first thing.

wsmcycle

the rear air bag must not be leaking. it has been all the way up in the rear for three days. There must be a bleed off valve somewhere to operate when you press the lowering button. Can someone provide a schematic of the airmatic system please or direct to where i can see one. I am 100 miles from the dealer and the car is not drive able. perhaps somewhere there is a schrader valve to check the active system pressure that i could bleed off.

Thanks

starbound01

There is no bleed off valve. You have to have a STAR to manually relieve the system. Read all of the the foillowing before doing anything. When you lower the car as follows the vehicle will all but sit on the wheels. If your air system has failed and the compressor does not run, you will have to tow the vehicle to the dealer or fix it in place.

Did you raise the vehicle using a jack as i suggested earlier??? You want the wheel to extend down so don't lift it from a control arm. The extension will cause the sensor to think the car is too high and it will bleed the system down. I *think* you need to wake the vehicle up but I just can't remember - Open the doors to wake it up.

The fact the vechicle is staying up only means it is not leaking in the position it is in. That does not mean it is not leaking. And it indeed may not be leaking at all. But leaking is not pertinent until you get the butt end down. I still think your distribution block is the problem. When you press "lower" the air is purged there.

Purge via the distribution block:
If you look at the distribution block you would see plastic tubes running into brass fittings. One is the compressor tube. The remaining are for the air spring, one for each corner. You didn't say how many corners you have with an airspring. If you can figure out which tube goes to the corner that is too high, you can loosend the fitting and bleed out the air.

If you cannot figure out which tube goes to which corner you can bleed the air out at the corner:
Jack the car up as above and remove the wheel. Look at the air spring and follow the air line. It will connect to a brass fitting. Use a 10 mm wrench and loosen the fitting until you start to hear air leaking out. DON'T take the fitting out! When it stops hissing you know the air is out. (If you are worried about height and driving, bleed some off for a few seconds and check the height). Tighten the fitting back up as it was prior to loosening. It screws into plastic so be careful and if you strip it you will have to replace the airspring. Obviously this is not a recommended procedure.

wsmcycle

Great, I have read this completely.
I can not find your previous question about raising the vehicle with a jack.
But, i think that jacking it will tell us something and I will do it
Do you know where i can download a service manual for $.
where is this distribution box located? Is the pump near it?

starbound01

No idea about the service manual. I'm sure there is one, but you can also go to a place like alldata.com. MB may even have one like the Toyota technical site.

I didn't notice before that you have an R500 - same here. The distribution block is just above the compressor. If you open the hood and look to the right adn down of the passenger side headlight assembly you can see the block. The air compressor is below it and is accessed by removing the front part of the fender well. I'm pretty sure you can get at the distribution block from the top. You'll be able to see the plastic tubes plugging into it. You may have to remove the air intake horn but i am not positive and the vehicle is not in front of me. I also don't know if they are marked for the corner they go to. If you replace it, rather than the stealer, I'd mark the tubing well. Getting it wrong will lead to some strange height adjustments.

If you are under extended warranty, the repair should be covered. might be worth a phone call. Our distribution block was replaced under warranty.

wsmcycle

i found the box and let and released all four corners. closed them and turned on the ignition. All of the corner raised. the back Left and Right went all the way back up. the front raised also but not as high as the back. the car is pitched forward.

starbound01

Your front wheels need to be at correct height.

For the following, make sure you do not bleed any air from either front airspring. Your trying to isolate the rear issue and you don't want the front affecting the results. The fronts take longer to fill. If the distriution block is leaking internally, filling the front could over inflate the rear.

Bleed the air out of the 1 rear airspring, as you did earlier. Let the vehicle refill itself.
What happened?

Bleed the air out of the other airspring. Let the vehicle refill itself.
What happened?

wsmcycle

I had to remove the front coupling in order to get a wrench on the back left. I did release the back right first. I did not start the car with only it down. I will try that. It is the easiest one to access.

starbound01

I probably should have explained why the 2 tests.

While you could have 2 sensors broken at the same time AND the distribution block leaking, it seems statistically unlikely. Though you know your car... not anyone here.

The reason for removing the air and then letting it rise is to see what happens. If the sensor is good, that corner will go up to its correct height. The opposite corner is already over inflated.

If both go to the correct height then I would make an assumption that the block is the issue and its leaking by when the fronts inflate.

wsmcycle

the previous test resulted in a return to the same high condition.
When I pressed the "lower vehicle button", the system reports “being lowered”, that tells us that regardless of the leveling sensors, the computer is telling system to lower and that without affect. Therefore the problem must lie out at an end effector such as a stuck valve…. Not a level sensor. I believe this is a logical assement.

However seemingly contrary to this, the system wants the car to raise when the ignition is turned on (because the compressor raises it). This makes the first premise illogical. Something is invoking the compressor to raise the car when the ignition is turned on.

HMMM even thought the computer is telling the car to lower, something else is causing the compressor to raise the car. That could very well be a faulty relay.

In the morning, we lower the car and then remove the green relay before turning on the ignition.

Does someone have a schematic of the "airmatic" system they could point me to? please

starbound01

Thanks for the results.

My *opinion* is you have multiple issues.

1) The fact that when you start the car and the compressor comes on tells me you have a leak; the vehicle should not need to inflate when you start the car. I say this because the compressor turns off and the back end is already over inflated. Only the sensors shut the compressor off. To prove it, start the car and let it finish doing whatever inflation it wants to do. Accurately measure from a known point at each corner (like the fender edge). Let the car sit overnight. Accurately measure the next day. That should tell you which corner is leaking. Do yourself a favor and do a soap bubble test on the distribution block to make sure the leak is not in there. Look in your owners manual to make sure you vehicle does not lower when shut off. My Lexus lowers itself when off/parked of stopped because its so high up.

2) When you press UP and DOWN the vehicle tells you it is going up or down. If it doesn't achieve the desired height in the timeout window, you get the error message you see.

3) There are multple threads about the rear sensors failing (freezing up). Uncouple it and see if the arm itself will move. You'll have to pull the wheel to do that. If you support the vehicle by the control arm, with the sensor arm disconnected, you can move the sensor up to raise the vehicle and move it down to lower the vehicle. If it doesn't move the sensor or the distribution block is bad. Make sure there are sensors on both rear corners. Maybe someone here can confirm that it should have 2 sensors in the back. My Lexus only has 1 at the rear. If therre is only 1, I'd probably spend the $100+ to replace the sensor and see if that fixes the issue. If there are 2 you are still down to the sensor and/or distribution block. It behaves like there is only 1 but i have not actually payed close enough attention to both sides, and you may have different vehicle options than I do (like variable dampening, etc). I may have misled you on that.

4) Pulling the green relay will only prevent the compressor from coming on. Nothing else will change other than you may get the console warning to take it to the shop.

wsmcycle

1) the compressor came on upon start up ONLY when i had let out all of the air from the four corners. Once they are up, they stay up and restarting the car does not turn on the compresssor.
2) When I press up, the dash message says rising.
when I press down, the dash message says lowering
There is no elevation movement in either case.

ONLY on the night this all began did i have a "warning message". it said "vehicle too low, raise vehicle". So, I pressed the raise button. This is when it rose all the way up.
I have not seen a warning message since that night.
I thought i should correct these facts.
Thanks for helping me

starbound01

I'm going to measure my wife's vehicle tonight and I'll let you know whatthose measurements are. Your vehicle may be somewhat different, but not by1-2". When I replaced the rear air-springs I thought for the longest timethe rear was too high but I am used to it now and if I look at the ground andbase of the vehicle it looks level. The air-springs may have been leaking andcausing me to be deceived by the change after replacement.


I measured: 32" in the front; 32.5" in the rear. From the floor straight up thrpough the enter of the hubcap to the edge of the fender. The measurements are well within 1/8 inch.

One other note... when you are trying a DIY repair on a hi-tech vehicle likethe R, you have to be very methodical. A STAR allows you to manipulate thesystem independent of the internal system. You have no way to do that as a DIYso you have to understand how the system works and create scenarios that testthe computers processes.
The corner sensors cause the corners to raise and lower. Pull the wheel,locate the sensor, disconnect the arm and manually move the arm slowly and seeif that happens. If you move the arm down the vehicle should lower. If you move it up the vehicle should rise. Ifyou question the rationale of that, go to the front and do it on 1 corner. Youknow that the front is working correctly so you will see the result. The rear behaves the same exact way.

Since the corners have independent sensors the corners moveindependently. If you move one sensorand other corners move, the distribution block is leaking. It's the only source of air for the cornersso there cannot be an alternative way to move.

You're not following the testing processes to the letter so it's hard to sayif it's a sensor or block.
I still stand by my leaking air-spring opinion, but that is not important atthis stage since the system itself is not behaving correctly. If you take it to the dealer, I think theywould call and tell you that you have a bad sensor or 2, they'd replacethat/those and then call to tell you that the distribution block needs to bereplaced. This seems to be the solutionthe dealer comes up with, if you read all the threads - which leads me back towhat I said server posts back about leaking springs, water in the system and failedcompressors.

wsmcycle

yeee haaa
got er fixed. crawled under the car to inspect the sensors (i had previously checked the back right) and found the back left sensor was missing a bolt and twisted upside down.
I bought bolts from the bolt house, put it back on and now it works. Up and down. I still don't understand why both rear corners were lifted when only one sensor was messed up but they both work now.
Thank you for your help starbound01

starbound01

Glad you got it fixed.

I think that both sides are rising because its leaking internally at the distribution block. But it sounds like it may be a presurizing leak and maybe its able to recover after the compressor shuts off.

Pay close attention to how often your compressor runs. You should hear it run when you press UP on the height setting, if you put a lot of weight or if you slow down from highway speed (unlikely you should hear that and I wouldn't worry if that happens.

Right before the leaks got significant, I would hear it run occasionally when my wife pulled into the garage. 2 things happen when the compressor runs a lot. 1) It burns up because its a light duty pump and 2) you get moisture inside the airmatic compoents which leads to rust, etc. Get you base measurements and use that for a basis every once in a while, to know if any of the corners are falling. Self leveling hides the sins of fine leaks until you get a failure.