CLS55 - What's the chances of the airmatic and SBC pump both going wrong?

[Nat]

On the way to the south coast to get my 55 serviced this morning and it pinged up with three messages at different times.

1st - add one litre of oil. No problem it was on it's way to getting an A service done
2nd - heard a hiss front the front then white message with visit workshop with an arrow pointing up.
3rd - red message reduced braking.

I stopped straight away on the 3rd message. Turned it off, checked under the bonnet and around the car for anything noticeable. Nothing obvious. Started it up and all seemed ok then drove off again then the white message stating visit workshop with the arrow pointing lit up again after 10 minutes. I mentioned this to the garage when I dropped it off and it was no problem for them to look at it.

Garage with STAR hooked it up.

The airmatic showed result of test - component A9/1 airmatic compressor unit does not function properly, then goes on to list 6 possible causes inc check air intake system, leaks, level controls, pressure relief and so on.

The SBC showed up fault codes stored
C26FB - Control unit A7/3n1 (SBC control unit) internal fault
C25D6 - This fault can be ignored and erased
C26DE - Hydraulics fault: Malfunction in pressure supply
C26BA - Hydraulics fault: Malfunction in pressure supply
C269A - Hydraulics fault: Brake operating unit

I'm not questioning the integrity of the garage by any accounts but has anyone had or heard of this happen before as it seems a bit odd that both would go at the same time on the same day.

Quote for new SBC pump, airmatic pump, couple of rear brake hoses, brake fluid, prop coupling all in at £1900. My only reservation and fear is that I get the work done and I still get the same issues coming back.

 

[AMGeed]

Re the third message, get both the Aux and main battery tested. Not just a volt meter but a load test and see if the CCA meets the battery spec.
Also get the alternator output checked with a voltmeter and the car running. Should be showing 13.4v+ up to 14v+
Once that's done and if you need a new battery(ies) at least you can rule out the SBC pump which is more than a coincidence getting the warning at the same time as the airmatic pump.

If the SBC pump is found to be at fault, forum member on the other side can possibly refurbish your unit for a reasonable cost
https://www.ecu-repair.co.uk/shop

 

[merc85]

Tbh £1,900 to get that lot sorted seems a good price,

Certainly worth getting the batteries checked 1st before replacing the sbc unit.

 

[Alex]

It looks like the garage just chose to replace everything that complained. Rather than try to find why it happened. I’d want a second opinion before throwing £2k away.

 

[E55BOF]

On my SL500, in the previous owner's hands the SBC unit failed as he was on the way to have the ABC (not Airmatic, but coilless suspension also) sorted out. He needed both the SBC and ABC pump units replaced. Remarkable coincidence, but yes, it can happen.

You state the messages came up at different times. How different? Thirty seconds, five minutes, half an hour? And which came first?

If the batteries and alternator output are OK, since the SBC unit codes were all stored codes it has/had an intermittent fault. You could carry on driving and hope it doesn't recur, but I'm not sure I would.

Regarding the Airmatic pump, did the garage check out all the possible causes identified before suggesting that it needed a new pump?

 

[KillerHERTZ]

1st point will be to check the batteries as per messages above. A low voltage will throw all kinds of errors.

 

[Nat]

Thanks for your replies. I've attached a couple of bits of paperwork they gave me but I'll have a chat with them tomorrow to see exactly how it was diagnosed. I guess I was wondering if the two could have been connected through something other than them been at fault.

From the return trip yesterday and today the airmatic lit up after 5 minutes or so and at no particular or reocurring speed. It made a hissing noise the same time as the message came on that sounded it came from the passengers side front. Turn it off and restart it then 5 minutes later it will do it again. It sits fine, it doesn't drop on any corners despite how long it's left for, it raises up ok and the sport 1 and 2 work. Or at least it all seems too.

I never had the reduced braking in red come up since yesterday morning or today. I checked the front auxiliary battery that is a Merc one and it sits at 12.69v and I presume the date printed on top which is week 50, 2014.

Since starting to type this post I've gone back out to it to get something out the rear drivers side after unlocking and opening the door the red reduced braking light lit up on the dash. WTF?

 

[AMGeed]

Have you checked the main battery voltage at rest Nat?

I just replaced the Aux battery on my E55 which is being picked up by the new owner shortly. It wouldn't hold a charge over 4 days and it was an OEM 2014 battery.

 

[Nat]

Have you checked the main battery voltage at rest Nat?

I just replaced the Aux battery on my E55 which is being picked up by the new owner shortly. It wouldn't hold a charge over 4 days and it was an OEM 2014 battery.

I didn't think of checking that one as I replaced it earlier this year but after your post I did and it's at 12.4v and 14.4v running. I think I might leave the car for a couple of days then check it again to see what's what then. If it is a duff battery at the back would or could it cause these problems?

 

[mersum1es]

Aux battery should drop back to 'sit voltage' after few minutes, it is charges only shortly after start. If aux battery is faulty it could rarely 'drain' alternator charge current. If you can repeat display message every 5min after start, measure voltage when fault appears. Check grounding of SBC unit (and why not engine block earth strap), there has been corrosion issues.

 

[Gbrowncls55]

The SBC pump can fail but usually the warning comes up because the pump has reached its maximum allowed number of pedal compressions set by MB as a safety measure. However that usually throws up a white mesage not a red. Did you notice reduced braking at all? Without the SBC pump working you only get about 10 % so you would notice. The fact the you heard a hiss would indicate an airmatic leak of some sort.Is the car noticeably lower?
I have just replaced the SBC pump only on my wifes SL at an indie at about £1200 if I remember so your estimate for all that work looks pretty good.

 

[Nat]

The SBC pump can fail but usually the warning comes up because the pump has reached its maximum allowed number of pedal compressions set by MB as a safety measure. However that usually throws up a white mesage not a red. Did you notice reduced braking at all? Without the SBC pump working you only get about 10 % so you would notice. The fact the you heard a hiss would indicate an airmatic leak of some sort.Is the car noticeably lower?
I have just replaced the SBC pump only on my wifes SL at an indie at about £1200 if I remember so your estimate for all that work looks pretty good.

Yes, I noticed the brake pedal more or less to the floor and had to stamp on the brake pedal. I turned it off then on then no warnings which made me think that surely if the unit was US it would have occurred again straight away. Reference the airmatic and like you say the hiss to me would point at a leak.

I'll go out and check the batteries again in a bit.

Out of interest where did you get your SBC pump replaced?

 

[mersum1es]

Lets not forgot the most common SBC failure; rear brake pipe corrosion where pipe goes behind the plastic trims... leaky pipe triggers main unit fault code.

 

[Nat]

Just doing an update as we all love updates.

I've had to have my SBC and airmatic pump replaced, along with rear prop donut (advised when from service) and while I was at it, I had the front discs/pads replaced although it was just an advisory for the MOT done the other month. I covered 1600 miles last year but that was mainly due to doing more miles in my other cars and motorbikes.

Car drives lovely and although that lot wasn't cheap, I'm happy it's all working well

I just need to clean it up as it's filthy in the weather we've recently had.

 

[Gbrowncls55]

I know I am too late but maybe for the future,If you are in North Hampshire then nobody does 55ks better than Ollie at PCS in Horndean, I had mine done at TM Motors in West Molesey who have looked after all my MBs and come very well recommended on here.