S212 2015 Airmatic failure Xmas Eve!

[Jswd32]

Hi All, Well my Christmas present was an airmatic failure on Christmas eve of all things. The rears had both dropped identically, to just within the arches and the fronts were low enough to hear rubbing on full lock. I was able to get home luckily and park on my drive. On Christmas day the rears had dropped further and it became un-driveable.

I noticed the airmatic compressor was not working anymore and had the yellow malfunction error in the dash. I checked the front airmatic fuse and the rear fuse and both were fine. Not being sufficient to check the Relay, I bought a new one from Mercedes in between Christmas, no joy.

I initially thought it was the Compressor pump gone, so after reading numerous posts online about these being fairly robust, I removed mine to bench test. I can confirm the pump works fine with a 12v supply as does the solenoid relay for the motor. I could hear the relay clicking in the boot also. I'm not sure if that helps someone diagnose or eliminate a few things? I thought I'd eliminate the potential for the rear level sensors to be broken, and can confirm on inspection they are both intact and the newer metal kind.

I then read numerous reports of how the fine wires that go from the compressor solenoid are a usual culprit and so opened up the sticky fabric tape to check these. I could see a little colour of the wire shroud, before removing, so could see they had been rubbing. I had read that these wires can break internally, so replaced a large section with the same gauge wire. Still nothing.

I have so much to do in early January and was hoping while marooned over the xmas period to get to the bottom of it. It now looks like I will have to either get it towed on a flatbed to a merc specialist or find a mobile merc mechanic to run the diagnostics.

I have heard about a 40a fuse failing and a control module failing under the front passenger footwell? but at this stage I would be guessing. I'm glad its not the pump thats failed, but am now stumped as to home DIY options.

My next thought was to check the wiring behind the rear bumper as it runs into the bootwell. This seems extreme, but I have a failed radar sensor I have ready to replace, so need to get behind there anyway.

Anything else worth a try before I spend hundreds on flatbed recovery, workshop time & a hire car cost while I wait?

TIA


Jonathon

 

[Jswd32]

OK, just thought this over a little more. I got in the car this morning and started it. All I could hear was the Relay in the boot clicking. So this to me signifies that the fuses are all correct and working, the Airmatic Pump is being sent instructions from the ECU to turn on, but the signal is not reaching the Compressor.

This makes me think it can now only be either the line between the Relay and the compressor solenoid, the line between the main power cable to the pump, or the compressor solenoid itself? I did put power to the solenoid and heard it click each time. Have I missed anything else in between?

I think my next step will be to use a voltmeter on the compressor connections, to see if power is coming through after switching on the car.

Kind regards

Jonathon

 

[Jswd32]

Anyone know if a faulty valve block would stop communication between the relay & the compressor?

Also if replaced and the problem part, would the car work again without needing to have fault codes removed?

Thanks

 

[ioweddie]

can you hear the compressor kicking in at all. I'm pretty sure the Valve block only distributes the air to the bags. My C220d S205 needed a new compressor. but I still had the occasional suspension dropping. so I got rid

 

[Jswd32]

can you hear the compressor kicking in at all. I'm pretty sure the Valve block only distributes the air to the bags. My C220d S205 needed a new compressor. but I still had the occasional suspension dropping. so I got rid

HI,

Nope no compressor kicking in at all.I have bench tested the compressor and it works, I'm thinking it now may be the solenoid switch on the compressor is poor as its not letting the power to the compressor.

 

[geoffr26]

I have exactly the same problem. The rear was dropping to the stops after 2-3 days not being driven before Christmas but its would always refill the airbags. Now when I switch the car on it says the vehicle is raising but the compressor not coming on. Valves are working, compressor works under direct power on the bench, relay is fine... I'm completely stumped

 

[Jobsworth]

Seen a couple this week following the recent cold snap. I think moisture in the compressor froze and they’d blown the big 60A triple fuse in the bottom of the front pre-fuse box. It’s underbonnet, part of the jump terminal. Be warned, you can’t buy the triple fuse from Mercedes