SBC failure
 

Well, My E320 Designo interior, which by the way it`s a beauty to drive and to see, it`s a real nightmare reliability wise. It only have 26k miles and I already changed the rear pneumatic shocks ($ 600.00 here in Mexico), all brake pads, tires (OEM are a p.o.s.).Yesterday whenI was taking the car to the dealer in order to do the scheduled maintenance a red alarm apeared on the dash, SBC failure,I found myself without brakes injust 2 seconds,I pulled over and turned it off, started it again and the brakes worked again, my confidence in this car NEVER. The dealer is asking almost 2.5k to replace the SBC unit. What can I do? It must be some responsabilityfrom Daimler Chrysler to fix this mess.I love the car, but I can`t spend all my life repairing it.And now it poses a real danger for me and the family, not to mention other cars and pedestrians.

RE: SBC failure
 

Hi,

IMPORTANT. The brakes continue to work during an SBC failure ALTHOUGH the pedal effort will be MUCH HIGHER than normal. Customers say the brakes don't work! They DO BUT the reduced performance (no assistance, just secondary hydraulic actuation) CAN BE frightening since the car does not stop as you expect!!.

SBC (brake by wire!) has been the source of many problems for MB.

If the car has done 26k without problem it is UNLIKELY that it is the SBC units are faulty...although not impossible. (i.e. Both computer and valve body). However establishing whether the vehicle has any recall actions regarding this problem is an important step. You may find that USA recalls are not honoured in Mexico since both the technical and legal systems MAY BE different.

I do not have much information about this problem but a number of MB service bulletins have been issued. My understanding is that one of the contributing factors is the alternator / battery. Are you SURE these are in 100% condition. If low voltage is experienced the system trips out. What speed etc were you travelling at when the problem occurred. Low speed? Did you have high electrical load. Air con, headlights, defroster etc? Have you had any starting problems or flat batteries. Once a battery has gone flat IT IS NO LONGER RELIABLE due to irreversible chemical changes. It may appear to be OK for some time BUT can easily lead to this sort of problem.

Several changes have been made to the valve body but if all has been OK for 24k miles then why should the unit suddenly fail. MB parts are usually extremely reliable.

I suggest your best bet is to contact MB or a main dealer with STAR Diagnostics (not a simple OBDII scanner) and get the codes read. This MAY cost a few dollars but it is an important first step otherwise you are shooting in the dark...and this is BOTH frustrating and potentially very expensive. Who's going to spend 2500USD WITHOUT some form of RISK ASSESSMENT that changing the unit will correct the problem!

Do you have any further vehicle / fault history. How long have you had the car, has this occurred before / since. Any special conditions relating to the failure, vehicle age, number of owners, did previous owners have the problem etc etc?

Occaisional "glitches" CAN occur in complex software of this type (and this is often why a new unit may resolve a problem) but its more cost effective to ensure the latest software is flashed.
I suspect that the system worked as designed and encountered some transient condition...like low voltage or other NON PLAUSIBLE input...that turns the system OFF since unless voltage is correct the system can't work correctly and may fail in an UNCONTROLLED manner.

I'm really interested in this type of problem since you are not alone and there is little factual information regarding the problem. BRAKES are a very sensitive issue and MB are not surprisingly tight lipped about the problems that have been experienced.

Stuart.

RE: SBC failure
 

the emergency brake works only on the front wheel.

sbc hydraulic unit is the cause of this.
there was even a recall. i've chaged so many. it's faulty.

try to apply for a goodwill if your mileage is low, and mercedes-benz dealer will fix it for free.

RE: SBC failure
 

Hi Sleepwalker.

I agree that the brakes work only on the front axle if SBC goes off but this doesn't impact the emergency feature. The problem is the VERY different effort required on the brake pedal. The customer believes he has got btotal brake fail since they are not use to pushing so hard. It an expectation issue.

Part of the recall was to change the unit so the unit SHOULD have already been changed. The reason for change wasn't so much a failure but a manufacturing fault.
So why has this vehicle covered 26 miles and X yearsk without a problem up to this point OR is the vehicle new to this customer and has infact had a problem throughout its life. This is why I asked for history?

The second part of the "fix" is to the electrics/.alternator (at least on the SL)
I agree that approaching MB is the best option but if it were my money and the problem has only occurred once in 26k miles and the recall has been actioned then I would look for a cause other than the valve body.

Stuart

Stuart

RE: SBC failure
 

26k is a low mileage and is still under warranty.

RE: SBC failure
 

Hi snanceki and sleepwalker. Thank you for your replies. You both are in part the cause I still drive MBs. I bought the car used about 1 year ago. I friend of mine ordered with Designo interior and paint, Avantgarde trim. It`s a 2003 so it doesn`t have any guaranty now. The dealer scanned the car after the incident and told me the new sbc would cost me 2,5k. After I start complaining the said they erased the fault codes and if the system fails again they will ask for authorization to replace the part free of charge ... but not sure.

My battery died about 7 months ago, i left the key in on position all night. No problems after that. The incident occurred when I was driving in urban traffic, 25 miles per hour or so. I was applying the brakes in a red light and it took a loooooong and SCARY way to stop.

I think the recalls doesn`t apply in Mexico, don`t know, the dealer never tells you. The applied a campaign, that`s how the call it here, to the car software in order to fix the crazy radio ... it`s still crazy but I get acostumed to that.

Braking is another sort of problem, I need to know what to do. I don`t want to get rid of this car. What do you think. If I have to replace the SBC what it`s the cost in the US, I constantly travel up there.

RE: SBC failure
 

the electrical load was: aircon, headlights, radio. outside temp about 25 degrees celcius. Previous problems with this car: crazy radio, rear and front airmatic shocks (expensive ahh), brake pads, tires.

RE: SBC failure
 

SBC is a safety related item and braking is very important.

all over the world, if your car carries the mercedes-benz star... will be treated the same.

just go to the dealer and apply for "goodwill".

RE: SBC failure
 

that`s what i will do, should i have to wait for this to happen again or go to them already?

RE: SBC failure
 

Well, finally the dealer changed the sbc unit, the spare was "free" and 300 usd for labor. Anyway I feel a little safer now. Thank u all guys! Car was delivered in 2 days and clean.