chris_e500

I have a problem with Airmatic. I’ve had some problems previously, but I’m struggling to diagnose this one.

About 4 months ago I started getting the odd Aux Battery errors, telling me various facilities would not be available. It would recover each time. I used the REST (residual heat funtion when parked) function a couple of times last week and when I returned to the car the Aux waring was on again.

Last week I started to get the Airmatic warning light (car graphic with up arrow) and the message ‘visit workshop’. It came one 2 or 3 times but cleared each time and no noticeable reduction in ride height and the compressor did not seem to be running any longer than normal (suggesting no air leaks).

On Friday I got the ‘stop car too low’ message and the front and rear were down on their stops.

Now, all last week it has been getting increasing cold (coldest in many years) here in the UK, with the coldest day on Friday (about -6 to -10 deg C).

Current situation is
• The Car is down at lowest level, bottomed out on ALL four wheels
• I can hear the compressor cut in when I push the brake pedal (every 10th press or so), but only for a second or two then it stops (this has been normal since I’ve owned he car, 30 months now).
• If I try the various ride height settings, nothing, still bottomed out.
• Visit workshop (Airmatic graphic) comes on if you try to drive it away, but not the 'car too low' messge, even though it bottomed out
• I can hear ticking from each strut in turn (from memory this is what you hear if you change the ride height)
• I can’t hear any leaks

From what I read here and elsewhere, I think it could be:

1. Faulty relay
2. Faulty fuse
3. Bad wiring around the pump
4. The cold (and damp) weather
5. Faulty pump
6. Faulty control unit
7. Possibly linked to the Aux battery

Does anyone know the answer to any of the following, that will help me diagnose the problem:

A. Where exactly is the relay located, I think its called K67 but I can’t find it’s location
B. Where exactly is the Airmatic fuse (40A?), I think its in the passenger foot-well
C. I think others have said that the Airmatic pump is on the Driver side (this is a UK model, so RHS), behind a cover in the wheel arch, between the front of the front wheel arch and the front fender?
D. Does anyone know if extreme cold (and damp) weather can cause the air-lines or pump/actuator to ice up?
E. Given that the symptoms have changed (visit workshop message with no loss of height, then ride height too low with loss of ride height, now no message and no height at all) is it possible that the electronics (Airmatic control unit) could ‘lock-out’ requiring a workshop reset?
F. The compressor noise I hear sometimes when I touch the brake (static or driving), is this the same compressor that controls the suspension? I’ve always thought it was, if so, it’s working.
G. As far as I know, if you had a leak in the system, it would not stop all four air-springs being pumped up, just the ones associated with the leak as the system cycles around each strut so at least 1 would work, is this a true assumption?

Any help with this would be greatly appreciated, I promise to document the root cause when I find it.

Thanks in advance

Chris

vettdvr

Just because you "hear" a motor running it doesn't mean the airmatic compressor is running. Leaking down and resetting doesn't mean no leak. Mine did that for 3 months before the dealer could confirm and replace the rear air springs. continute running with a leak could result in failure of the pump. The air bags fold and in the fold can deveop cracks which will seal a bit enough to allow the compressor to catch up. Park, cool down the leak opens and loses pressure.

So Don't assume:

1) you have no leaks
2) your compressor is working.

You must do a leakdown test to determine if it holds pressure and my dealer did this test. If you have no leaks the you must confirm the compressor is producing pressure and not just the motor runnings.

So make no assumptions.

What you know

1) you have been getting a suspension alarm
2) the car lowers on all 4 wheels
3) you hear a motor running.

Lots to work on here to get to the bottom of it. Hopefully this items will help you confirm what is really happening. Best of luck.. vettdvr

MB211

BTW, a pump noise heard after every several aplications of the brake is likely the SBC pump-----the airmatic pump is pretty quiet an is unlikely to be heard in the cabin------

Also, cars typically do not fix themselves. If you are receiving a warning message, and ignore it, you are openning yourself to further repairs due to consquential damages.....

konigstiger

http://www.benzworld.org/forums/w211...ml#post3918102

chris_e500

Thanks Guys

VTTDVR, I agree with your summary, and I now know the noise is the SBC (brake) pump. So the symptoms are down to just two.

Konigstiger has offered to send me the leak test procedure, so I'll do that (as well as checking the fuse/relay/pump.

MB211, I agree with your comment that cars do not fix themselves (so act on the messages), but I suspect many people hold back taking the car to the dealer in fear of an 'avoidable' bill. I've taken cars in before now with error messages and have been charged almost £100 ($180) for the guy to tell me "no fault found, we reset the errors"... twice now... Doh!

Thats why I want to invest in a code reader, any suggestions welcome, hand-held or PC based?

BTW... It'll be interesting if the Aux Battery message is linked to this fault, its been in for a service since I got the battery message and they said it was OK.

I'll post the outcome, either way.

Cheers

Chris

mcleantmw

In my case, the Airmatic pump was operating but became defective, not pumping enough air, and had to be replaced. Some Airmatic pumps are noisy when in full pump mode and I can hear it, other times not. It's in the lower right (driver) side of the engine compartment. Your SBC pump can be heard, too, but it's located in the left side of the engine compartment.

herrakani

I had a similar problem on a ML63 when it had a leaking airbag. Seemed the pump gone wrong from constant pumping.

Diesel Benz

I think your left and right are reversed, you must mean "when looking at the car from the front" (which makes the real left a right ).

mcleantmw

Thanks for the correction...........I did mean when looking down into the engine compartment while standing in front of the vehicle. It's easy to get that confused and that's why I now add driver's side for clarity.

MB211

Drivers side is relative to where you live, I think the OP mentioned UK........The only part that you could correctly state "drivers side" on both cars is the steering and throttle controls!!!

chris_e500

An update.

Ran out of time on Saturday and NEEDED a Car Monday so decided to take the Car in and let the dealer do it (they provided a loan Car).

They diagnosed a faulty compressor, but interestingly changed the relay (green Hella with P/N A 002 542 23 19 embossed on it).... Hmmmm would have though one OR the other, not both. Anyway, got the two parts back so will test them.

Costs in case you are interested

Diagnose: £80 ($130)
Fitting: £89 ($144)
Relay (P/N MA 002 542 72 19 ) £8 ($13)
Compessor (P/N MA 211 320 03 04) £252 ($408)

When I reported suspension warning messages previously, they went and changed the pump (under the MB UK used car warranty), the one in my hand has a manufacture date of 14th Oct 2007. I can't recall when it was changed, but clearly there is no way it could have lasted any longer that 14 months, but I'm suspecting it was more like 18 months.

This leads me to think that either the compressors are not up to the task, or there is perhaps a leak, always has been and thats whats making the comressor fail.

I that despite spending over £400, I've not heard the last of Air suspension problems on this car ;-)

chris_e500

Just put 12v on the pump and works fine......

Anyone know what the other connection is? It looks like a solenoid/valve and I suspect that is OK as it measures 15 ohms.

Just check the relay, that looks OK too..... Hmmmm

I guess I'll just have to try fitting the compressor to the Car.

chris_e500

As suspected.... after a week, I've noticed that the left rear loses about 1 inch of height overnight. I suspect this was the problem all along and thats what's caused me to require two compressors in just 18 months.

This seems to be a common complaint, you'd think the workshops would spend a little more time looking for the root cause (inc air leaks)..... Looks like I'm going to have to pay for a pair of rear air springs, but I could have saved the cost of a compressor being fitted!!!

konigstiger

As previously explained strut leak you found may have caused the compressor to fail therefore, you may have had two malfunctions. Present a copy of AR32.22-P-8100T I emailed to you to the service manager and question if they performed this mandatory procedure more so since they replaced compressor twice. If so, have him show you documentation (i.e.: invoice narrative). If they cannot provide proof contact MB to request goodwill repair in light of the dealer misdiagnosing the repair worst-case scenario they may provide assistance (i.e.: cover part cost) for strut replacement. If mileage is 50,000 miles (~ 80,000 km) MB recommends both struts be replaced.

MB211

Usually a failed compressor damages the relay. Pull apart old relay and you will see contacts being burnt. Either way the $13 is cheap insurance on new pump.

Some leakage sitting overnight may be normal. I would assume (you know what that spells) they did a leak test on struts and valve and found it to pass. The repairs are being paid for by you not them, why would they not want to get paid for additional repairs if needed?

I would hope they changed the relay during the first repair. Damaged relay may cause compressor to stay on causing it to burn out. WIS instructs pump, relay and fuse to be replaced in event of compressor failure....

vettdvr

Right on target again. Exactly what I experienced and had corrected.

chris_e500

I had the following on my 2003 E500

1) Began getting suspension warning, called dealer on cell at first alarm

2) Took car in for check out... could not duplicate

3) Car continued to be low on the rear after sitting overnight

4) Took car in with alarm still in FSS and service mgr saw alarm and documented it.

5) Called to pick up car after new compressor and relay changed.

6) When the guy drove the car from the wash rack he asked me if it was a
lowrider. because the rear air springs had totally collapsed.

7) Service mgr came back out to see it and sent it back into shop.

8) New air springs both sides replaced (83,000 miles CPO warranty).

9) 1 yr later no more issues

The leaking air system will cause the compressor to exceed it's duty cycle an fail. This is a normal failure mode. But replacing just the compressor does not correct the problem if you have a system leak. The leak must be corrected.

ThumpaS550

Ive heard many people talk about doing this but can’t find a tutorial? An explanation would be very much appreciated as I’m having these problems with my 07 S550. Ignored the malfunction message every time I drove as I knew I had a bad consumer battery and thought it was sending a false warning. The car dropped on both sides in the front end and then the back end followed suit after a few days of sitting. Changed that battery and it didn’t fix the problem (long shot) but I’ve heard of a few cases of battery being the cause. I would appreciate if you could tell me how to apply power to the pump so I can try to narrow down what’s needing replacement.