Zach8131

I have had this issue before on my x164 GL, w211 E class (rear), and a w220 S class.

I found that on the x164 GL and the w220 S, the valve block was to blame. I learned not to buy aftermarket "brains" for the suspension system. A lot of people have good experiences with Arnott but I have not had good experiences with their valve blocks. Replaced with a genuine one and all was good. It turns out that the vent-valve that lowers the vehicle when you exit did not seal off and was causing the front end to leak completely.

For the E class when we replaced the rear air springs we tightened the line going to the reservoir tank all the way but the air line itself had tension in the opposite direction which slowly turned the fitting out. I took the line out of the valve and allowed it to release the twisted tension and reinstalled. Fixed.

Hopefully this gives you another direction to look into.

Cheers!

cartunes25

I can also confirm that the Arnott products are not good, especially for the GL Class. I found this out the hard way.

Green Guru

Ok, wondering if my sensors are my reoccuring "Airmatic Malufunction" issues. Have had nothing but trouble with this 2008 CDI. Replaced Arnott pump 3 times. replaced supply block once. replaced RL Airbag, recently had FR airstruct leaking to audible level. Blew compressor before part could come in. Warrantied compressor, replaced struct, relay and pump. Turned it on, it blew fuse. Checked continuity on Positive to pump. Checked continuity through relay to pump. Checked grounds to pump, all good. Sent replacement pump back to be replaced just in case same issues. Pump will not turn on. Did MBII scan, saw really low readings on FR sensor and RL sensor, just replaced FR sensor and no changes. Checked Codes, Saw front sensor, cleared, and resarted 5 times amd pump still doesn't turn on. No errors. Going to replace RR sensor tonight, but am concerned it is something else. Here are my scan details. Also checked battery compartment to see if there is the pontential for any water issues at my Airmatic controller which i understand is under the driver floorboard. Anyone ever had this level of issues or any suggestions???? Previous to latest fast leak on Airstrut. I Have been having the "Malufunction" light come on ever time I raise the suspension. More recently I have also gotten the "PUMP COOLING" warning. Any advice welcome as the closest dealer is 2 hours away!!!

cartunes25

Hi Green Guru,

I am not familiar with your scanner. Does it have any diagnostic modules for your model? Is there a suspension calibration test. This would run system in order to calibrate the corners and sensors since as it seems now you are getting false readings in the rear unless you are not parked on a level surface or have a bad sensor or broken arm that attaches to the control arm.

It would be beneficial to fully check everything for the pump including wiring, the fuse, relay and grounds. With the issue you had it could be that there is no power to the pump. The scanner should also have testing for such things as pump check and if you have all 4 corners on jack stand, a valve check. Pressure tests, how long does it take to get to operating pressure. Without all these tests done and multimeter verification of the level sensors and results provided, its hard to guide to a next step.

If you plan to keep this vehicle, it will help to have a service manual on hand. Even if you dont do your own work, it can help you to make informed decisions about the shops proposed repairs.

Green Guru

MBII iCarsoft scanner was used, doesn't seem to have any calibration options for Airmatic, went through every option. Restarted multiple times and tried again just in case, ran scans again, got LINE LEAK message, cleared, tried again multiple times, scanned, got no errors. Only front end is jacked up. I am assuming the pump works as it is the second one from ARNOTT, and both didn't turn on. Checked continuity from fuse out through relay to pump positive, so assuming something isn't happening on the other end of the fuse in side, we are good. Assuming now that either the Valve Block or AIRMATIC controller is not telling the pump to turn on for some reason? Have checked all wires to pump, sensor and block and all look good visually. Will do my best to check with multimeter, but not exactly sure what to look for. Any thoughts it might be the Valve Block? I did notice the Raise button at one point would not even illuminte, Then eventually after restarting again, it would, then flash then "COOLING" warning would come on. I also remember the valve block





is an aftermarket I believe. Also what are better options for pumps or sensors than Arnott? I thought they were the best. I did learn not to get Arnott struts and airbags and have bought Bilstein when replacing those. Any other things to check that will help resolve would be great, otherwise I am facing a 2 hour tow to dealer...

eric_in_sd

Get an AMK pump. I recall seeing the new Arnott pumps are AMK, after they realized the Chinesium they were selling failed after about 20k miles. But AMK pumps are available elsewhere for a few bucks less. The famed Arnott warranty is not so useful on the pumps, which last a very long time on a non leaky system. This repeats the lesson, like with the alternator and battery and starter, keep all three up to snuff together and all three will last longer.

Failure on the valve block is not that common. It tends to happen when moisture makes it past the pump, which has a dryer, so it tends to happen in leaky systems that are run without prompt repair, as the dryer gets overloaded. The moisture corrodes the solenoid valves. Humid environments hasten this process. To my knowledge no one on the forum has discussed the valve block, except that I bought a Chinesium one and found it did not work out of the box. If you get one from a respectable retailer, you might be okay. I'd be tempted to try a used one - but they are not all that expensive. Maybe try FCP Euro; they seem to vet their products well.

The consensus seems to be to get Bilstein rear bags, because you may need the pressure tolerance for things like trailer tongue loading, and Arnott struts for the front because of the warranty and acceptable quality - plus you get a rebuilt shock absorber with each replacement.

The MBII is a terrific tool, but it only reads and does not write. So you can't instruct it to manipulate the Airmatic valves, etc.

Green Guru

If not likely block, how do you test sensors and wires?

Could block being broken or corroded keep pump from even turning on?

Forgot to mention, I am in a super humid environment and make regular crossings through a small river ford. Luckily there looks to be no corrosion or rust when visually inspecting parts and underbody.

Can anyone please guide me through other things it may be?

1. If block, how to test? And would that keep pump from turning on?

2. If sensor somewhere out of the 4, how to test? Is there a certain continuity they should read?

3. If sensor wires? How to test after visual inspection?

4. How to test power to pump if fuse isn't getting power?

5. Would block have controls in it that would tell fuse and relay to send power to pump and if so, any ideas on testing?

Going back at it tomorrow morning with old block which I believe was never a problem but I swapped it when replacing the pump one of the 4 times it has been replaced. Also have another new Arnott suspension sensor and going to experiment with checking continuity on the new and old sensors to see if they are any different and swap if so. Will also check continuity and voltage along with grounds on sensors and block. Have already done so on pump (but can't get power to it, hence it not turning on).

Root question after all this, what would tell my pump not to get power? Keep in mind multiple 40a maxi fuses have been changed and relays to verify as well as continuity from fuse out through relay to power wire to pump plug verified. It is just that the system is not sending the pump the message/power to turn on.

Last question and concern, who knows anything about the airmatic systems controller under the driver side floor board? Any ideas? Could it be that? I was told to check for water in bottom of battery box as chance for water affecting airmatic control unit, but it was dry with no evidence so I would much rather not pull up my driver side floor.

Any more suggestions or tests appreciated! Thanks in advance and pray I don't have to have towed 2 hours to dealer and have them find something I somehow missed.

Green Guru

Ok, just swapped out used working valve block and still no luck with pump turning on. Then swapped out control module with used exact same part numeber working unit and the pump is still not turning on.

Any other suggestions appreciated, otherwise I have to tow to shop 2 hours away as I live in the middle of no where!!

Green Guru

[QUOTE=Green Guru;8639822]Ok, just swapped out used working valve block and still no luck with pump turning on. Then swapped out control module with used exact same part numeber working unit and the pump is still not turning on.

Any other suggestions appreciated, otherwise I have to tow to shop 2 hours away as I live in the middle of no where!![GL320 2008 replaced front right airstrut, compressor ran for a few days, blew fuse, replaced fuse and relay, tested relay, pump would not come on, had pump swapped for new pump, still would not turn on, inspected fuse box and all wiring, took apart, tested relay again, swapped with another new one, jumped power through relay, was able to get pump to turn on by moving around power wiring harness, must be short there, held in place for a while and pump was running and airbags were still not inflating. tested relay leads in fuse box, found 14v coming through 30, 86 and 85 both had around 4.32V and 87 had no voltage. Should bother 86 and 85 have low voltage? i think i understand 86 to be negative and 85 to be positive for the trigger? if that is the case would both having voltage make the relay not close and supply power to fuse then to pump. If i jump 30 to 87, i do get power to the pump, however as mentioned air bags still do not inflate. I also swapped my airblock module bag to the original one that i believe works as i had swapped to aftermarket a ways back when replacing the pump and there were no changes. also tried to swap out airmatic module under driver side floor and no changes, using MBII icarsoft and looking at data and codes. no errors showing currently. Any suggestions? something with the wiring to the relay?

eric_in_sd

Simply running the pump will not inflate the air bags. You have to also open the valves from the pump and to the appropriate bags. Here is the physical schematic:


I wonder if your front SAM is water damaged. It is under the driver's seat. The front SAM acts like a router. The fact that the dash button was flaky also makes me worry about the front SAM.

Did you clear DTCs from the Airmatic control unit?

I am mighty concerned by your "was able to get pump to turn on by moving around power wiring harness". Do you mean, with the relay jumped, if you wiggled around the power harness the pump turned on? It is possible you were just suffering with marginal connection of the power plug at the pump.

Make sure also that the intake air line at the pump is good. Mine was ruptured just above the pump. Replace the whole line from the pump up to the intake air filter with braided rubber. If the line is open the pump will suck in dirty air, which is of course not good.

Green Guru

Can you draw the wiring diagram that includes how the relay controls the pump? I am curious about the 85 and 87 wires and where they come from, like I mentioned i think the 85 is from the pump pressure sensor. Not sure about the other wire, they both get 4,32V which is weird and I am concerened. As for the front SAM, I did pull the AIrmatic Module and swapped, cleared DC and tried multiple times with new module and no luck. Where is the Front SAM and what part would affect the airmatic? I have replaced my rear SAM from corrosion.

Going to repair power harness to pump today and try everything again.

I have also replaced intake hose with braded hose already, great suggestion!

Anything else I can check and how do I locate, test or evaluate the front SAM?

eric_in_sd

Since you are by necessity self sufficient, you really ought to get yourself WIS. It includes wiring diagrams. They are difficult to navigate but once you get the hang of it they aren't too bad. You can get it on Ebay for like $5; it runs in a virtual machine on your computer. You need to download something like 50GB. Obviously not a legit installation, but MB does not to my knowledge sell individual licenses.

On the relay, it looks like 30 is the 12V rail, 87 is the switched out to the 40A fuse, and 85 & 86 go to the control unit. This is for my 07, which is probably the same as your 08.

There is no "pump pressure sensor". There is a vent valve at the pump. There is only one pressure sensor, on the valve block. After styudying the wiring diagram, I realized my physical diagram has an error. There is not a vent valve for the pump in to the valve block.


I do not know if the valve on the pump is normally open or closed. If closed, it could be damaging to the pump to run it without opening the vent valve. Be cautious when bypassing the relay.

Look for corrosion on your front SAM. It could be it is refusing to power the Airmatic control unit. The front SAM only appears once on the Airmatic control unit wiring diagram, so I bet that is its power supply. Look at pin 11 on the ACU, pin 20 on the front SAM.

Green Guru

Ok, spoke to another mechanic and he said front SAM has nothing to do with Airmatic. I am going to order WIS, used to have it, but got new computer and can't find discs. It will take a few days to get those files, if it is easy enough to screen capture and share the wiring or any other data details on the Airmatic, that would be awesome. Can you tell me where the front SAM is located? Is it under the driver seat? I pulled, inspected, and swap tested the Airmatic module under the driver side floor with no luck. Curious to look at the SAM as I did have corrosion on the rear SAM a couple years ago affecting the rear lights and hatch latch. If you can tell me where it is and how to accesss/inspect, I will take a look.

Second, what is the ACU?

I will look at the front SAM and ACU once I understand where they are

Lastly, what do you think about my 85 & 86 both having 4.32v when car is running? Is that odd or is that normal until the "signal" is sent? Curious what voltage that is and which one recieves the message?

Thanks again for your help and hope to have some updates later today.

eric_in_sd

ACU Airmatic control unit. Look at the pin-in as I suggested. The mechanic is wrong, as the front SAM is on the wiring diagram. What it does for the ACU, I do not know, but I would bet it provides power.

Front sam is under the driver's seat (so I have been told; I have never looked). It has an enormous connector going in. It is one of two hubs for a whole bunch of devices.

The wiring diagrams are a giant pain to ponder, let alone screen cap. The wiring diagram includes the optional ADS, and as you may remember if you looked at the wiring diagrams, they are distributed, with you jumping from diagram to diagram.

I don't know what to make of the non 12V measurements on 85 and 86. You did not say what they are relative to. The ACU provides the voltage across the pump relay coil, so you would have to measure one pin against the other, not to ground. But the first thing I would verify is that your ACU is getting power.

As you are doing all this stuff, I hope you have a trickle charger on your battery. Sagging battery voltage causes all sorts of mysterious behavior. These are computers, after all.

Green Guru

Ok, on the ACU. I assume that is also called the Airmatic Control Module and is the one mounted under the driver side floor. I did pull that and inspect thoroughly. No corrosion or any weird pins or burnt smells. I will check the pin you suggested on the ACU and also pull the seat to access the front SAM and inspect that pin as well.

Will get a trick charger on there, good advice!

Green Guru

Corrosion and Twisted Pin Connection At Pump Power Plug

As I have traditionally worked on a lot of older diesels, this has been a few new wrinkles in my brain working with electronic and circuit testing. It ultimately came down to the pump power plug having both corrosion and a twisted connection pin. After disconnecting and blasting with multiple shots of electronic cleaner along with some good poking/scrapping with the harness tools I had intended to pull harness apart (but could not figure it out, can anyone tell me how to pull this apart??).

After the cleaning up process, I figured I would give it a try. ONE BIG NOTE< Make sure to close all doors including hood and hatch otherwise Airmatic will not turn on.

AND IT FINALLY WORKED AGAIN!!!

Next, can anyone tell me how to take apart this type of power harness?? I got the pin kit for disassembly, but it didn't make sense.

Thanks for all that answered!

eric_in_sd

Seems to me you could probably reach into the female pin side with a jeweler's screwdriver and pry the sides of the socket together. I have repaired loose electrical outlets this same way, prying the wipers together.

a3grimlock

If the fuse (orange) is good the relay might be the problem. It’s in the same fuse box.

Green Guru

Ok, back to this fun project, ugh. The latest is below if anyone can add any insights it is much appreciated.

1. Got system running for a while, after replacing power harness to pump that seemed to have had one of the power prongs inside loose and slightly melted. Replaced wiring harness with new harness. Ran for a couple weeks, then compressor stopped turning on yet again.
2. Went through same process of checking, testing and replacing fuse and relay. No luck.
3. Tested harness with 12v and bridged relay with 12v, pump turns on fine.
4. Checked continuity on power to pump and it had resistance. Figured either it had rubbed and shorted or mice got at it (live in rural area where mice are a problem). Ran new power wire to pump. Tested with jumping relay with 12v, pump turns on.
5. Lower vehicle, remove battery negative cable for a few minutes, replace cable, close all doors, hoods, hatches, turn on vehicle, no pump. Also no errors except for bad generator (alternator).

I had replaced my alternator with a Chinese Alternator in a time of low cash flow and am thinking that may be the issue? Can anyone on here confirm if the computer is not getting the correct voltage or reading from the alternator, would that keep the Airmatic from turning on in order to protect itself and the battery?

I pulled the batter and did a refresh cycle on it and slow charge to get it back to close as spec as I could. I replaced the battery and the airmatic still doesn't turn on and I still get the bad generator codes. Going to put a Bosch alternator in there like I had should have to begin with and see if that does anything.

Any other insights would be helpful. Otherwise if I can't figure it out, I think I am going to have do the spring conversion.

eric_in_sd

When you have electrical problems, you always must establish a good baseline. Alternator voltage should be ~14.4V. For just a few bucks you can get a battery tester; confirm that your battery is good.

Green Guru

I replaced the alternator with an OEM one and still no luck getting the pump to turn on. Airmatic light just flashed slowly and no dashboard error codes.

Does anyone know which wires that go to the relay control the relay switch to provide power to the pump? If i jump the relay i can get the pump to turn on and run, but the vehicle will still not rise.

I a now thinking that maybe a control wire from the Airmatic controller/computer under the driver side floor mat/board may have a wire that runs to the relay to tell the 12v to go through the relay to fuse to turn on the pump. There must also be a wire that goes from the airmatic computer to the valve block to tell it how to distribute the air to the various air lines to various airbags.

I am now very concerned a mouse caused wiring damage to this part of the vehicle and am unsure how to address. I can maybe run new wires if i can identify them. I did replace the pump power wire as it was shorting and also the pump power harness, but there must be something else that is controlling the relay to provide power as well as something that is controlling the valve block to distribute the air (since if i jump the pump with power through relay or 12v test battery, the vehicle still will not rise).

So if anyone has any ideas how to trace and or identify and test the wires going to the relay to switch the power or and or what goes to the valve block to tell it to distribute the air, that would be amazing and I guess my next challenge.

Does anyone know if the airmatic computer has a wire that goes to both the relay and the valve block? Or does it only have a wire that goes to valve block and does that have a wire that goes to relay to tell it to switch power on?

I am at a total loss and have been dealing with this for a few months now on and off. The mercedes dealer 2 hours away say they don't have a tech capable of resolving this level of issue! They suggested another location in a larger city 3 hours away and i am yet to see if they are capable. They also said they are booking a month or more out.

Any suggestions would be much appreciated! Almost to the point of swatching out to springs, but don't want to lose airmatic functions as i do a lot of on and off road travel as well as towing.

Please help!!

eric_in_sd

Frustrating.

If you run the pump without opening valves on the block, the suspension will do nothing. It is also probably bad for the pump.

There may be multiple Airmatic dash messages, but one I know of is monitoring the pressure when the pump is filling the reservoir. If the pressure does not rise, it assumes the pump is bad or there is a leak. It does not have any way of verifying that the valve to the reservoir is good.

Have you verified that the valve block is good? Did you install a Chinesium valve block?

chassis

When was the main battery last replaced?

Green Guru

Thanks for these insights, so the valve block is MB/OEM. I had actually changed it to a Chineseium one a year or so ago when I was dealing with the pump running a lot and unable to spot a leaking airbag with soapy water, etc. Lessoned learned, that is not the best way. Now have scanner to see levels and live data.

I also changed Left Rear bag and front Right Airstut with Bilstien as I want to tow heavy stuff again!

It ran fine for a month or so, then just lowered itself slowly.

I sent arnott pump back for new one since it was on warranty. No luck at first.

I wiggled power input plug and got pump to turn on.

I inspected power harness which had loose and slightly melted power plug connection. I got new plug and rewired. No luck.

I checked continuity on power and ground and found bad continuity on power, so I figure a ground had occured and rewired power from fuse block power out to pump. NO luck, but could get to run if I jumped the relay to get power to fuse and pump. But no rising.

Back to the airblock question. When I put the china one it it ran fine. But didn't change anything leading me to think the MB/OEM was still good. Luckily I keep all my old parts just in case.

So to answer your real question, I actually swaped it back to the MB/OEM one a month or go during my multiple month battle with my airmatic (Luckily I inherited a Chevy trailblazer (dare i say redneck GL?), unlucky it was just a chevy). Anyway, the GL sits in the barn and I wrench, fix what i can from forum and other research, then cuss and swear when it still won't rise.

As for the battery, it is only 3 years old. It does look like the Chinesium alternator I put in back in April was failing, so I replaced with Bosch (fun job, not). I pulled battery and put on battery repair charger which goes through tons of cycles "restoring" it. It only had like 6V at 40% or something like that when I connected. After restorating, very slow and long charging it said was 100% at 12V. This battery has never been discharged before this event.

I had every hope in the world that putting the Bosch alternator and a recharged/restored only few years well maintained battery would be the magic formula.

I started her up last week and she ran great, but no pump!!!

Also after running for a few minutes a piece of the serpentine belt came off!! I ran over to stop and popped the hood. It just shredded a section, but most was still in tack. So new belt tonight as well as new tensioner pulley and bearing. I have also replaced all the seals on the throttle body and the boost hoses around the alternator and belt changing zone.

So.......

I did not have a chance to run my computure MBII icarsoft when she started up and I had planned to. Was hoping after pump not starting that just maybe, I had to run the scanner and clear some codes left behind from the failing alternator and it would then tell the pump to turn on. I will try this again.

However, this is what I really need to understand.

As mentioned earlier, I am able to turn on the pump by jumping the relay (bridging 12v input with 12v output). I however only get 4.3V readings on both sides of the relay switches.

So follow me...

I am concerned the relay and the valve block are not getting proper commands to turn on.

Just a reminder, I did swap out the airmatic computer under driver floor mat and tested the best i coul with no changes after multiple tries and computer reads and code clears.

Is there a way to test signal to air valve block and to relay switch wires?

Who can win this amazing opportunity to resolve this oh so wonderful challenge my wife is about to kill me for having to drive the kids to school in a chevy trailblazer 2008????

chassis

The battery is toast. Replace it.