SBC Brakes onW211

[Xtractorfan]

This does really not sound good.. I can share congo's lack of confidence, I quite like the 211 E Class and would have certainly have considered buying one.. But SBC brakes have ruled that out.. I wonder can a conversion be done..

 

[st4]

thats why id not be happy owning a car with the system. it could, in my mind, fail at ANY given time! i know normal brakes could too, but the failsafe of normal brakes usually cuts 1 circuit or its a servo failure. servo can be overcome to a point with lots of pedal pressure, circuit failure still leaves the other circuit and it works a bit harder. im not sure id fancy being at motorway speeds, as alfiebeard was IIRC, when the dash goes red and ive only 10% of braking! the foot operated park brake isnt quite as instinctive as grabbing the handbrake in such a situation, for me at least

incidentally, where did all the threads about alfiebeards sbc failure go? i could only find the one about the botched fitting of the replacement pump last time i looked for it!

Pete, I wouldnt go for the parking brake, I wouldnt want to lock the rear wheels @ Mway speeds and skid the car. 10% braking, and manual intervention to slow the car (with an autobox) is my course of action, or tap into and roll to a stop on hard shoulder.

 

[television]

This does really not sound good.. I can share congo's lack of confidence, I quite like the 211 E Class and would have certainly have considered buying one.. But SBC brakes have ruled that out.. I wonder can a conversion be done..

The servo is the main problem on the 230 ,,just nowhere it could go,,unless a special one could be made, and controlled from links or rods

 

[turbopete]

Pete, I wouldnt go for the parking brake, I wouldnt want to lock the rear wheels @ Mway speeds and skid the car. 10% braking, and manual intervention to slow the car (with an autobox) is my course of action, or tap into and roll to a stop on hard shoulder.

i wouldnt go for the parking brake that hard! ive locked rear whels before at near motorway speeds on the handbrake. you need to have your head well screwed on for that! id agree with downshifting, but id still prefer to deal with a standard brake type failure than the sbc type. yes theyre brilliant. just a bit too temperamental and complicated for my liking. if i bought a 211 or a 230, id be scared of it in case the brakes went, especially the way i drive!!!

 

[st4]

i wouldnt go for the parking brake that hard! ive locked rear whels before at near motorway speeds on the handbrake. you need to have your head well screwed on for that! id agree with downshifting, but id still prefer to deal with a standard brake type failure than the sbc type. yes theyre brilliant. just a bit too temperamental and complicated for my liking. if i bought a 211 or a 230, id be scared of it in case the brakes went, especially the way i drive!!!

The facelift 211 does without SBC, once depreciated a great buy for you.

220cdi with 6sp manual box is what you want.

 

[Xtractorfan]

Must have a good nosey round the next one we have in... Talking of that we did have a 124 in for repairs a good few years ago and as it smoked something awful when on cold start up we decided to just push it out of the garage..first thing in the morning.. .. so everyone pushing and the young apprentice steering.. ahh disater.. no brakes..hard pedal but no stopping power, straight over a very low wall and into a fence ....

 

[turbopete]

The facelift 211 does without SBC, once depreciated a great buy for you.

220cdi with 6sp manual box is what you want.

if i went to a 220 cdi though, i might just make do with a c class. although a 211 would be nice, i think the 203 or even a depreciated 204 would be that bit nippier!

 

[st4]

if i went to a 220 cdi though, i might just make do with a c class. although a 211 would be nice, i think the 203 or even a depreciated 204 would be that bit nippier!

A 204 is a fab drive, you'd really enjoy that.

Havent driven a 203 to comment on, but the 204s are lively!!!

 

[television]

This thread should not be mixed up with a 211 as it mainly concerns the 230 and this SAM when I do my test I will start a new thread

OK any SAM could fail at any time on any car,, but on the 230 we know that the passenger one often fails

 

[turbopete]

This thread should not be mixed up with a 211 as it mainly concerns the 230 and this SAM when I do my test I will start a new thread

OK any SAM could fail at any time on any car,, but on the 230 we know that the passenger one often fails

but surely theres the potential there for the same problem to occur on a 211 isnt there? or is it to do with the actual location of the sam in the 230 that causes a problem that cant exist in a 211?

 

[turbopete]

A 204 is a fab drive, you'd really enjoy that.

Havent driven a 203 to comment on, but the 204s are lively!!!

well i know what 203's are like. dad has one. that could be my next MB. at least i know its history, from 7,200 miles, at least!

 

[television]

but surely theres the potential there for the same problem to occur on a 211 isnt there? or is it to do with the actual location of the sam in the 230 that causes a problem that cant exist in a 211?

Yes as I said, the 211 does have the SBC running through SAM's but the SAM's on a 211 do not give much trouble.

On the 230,, the box is far too small, and the same box carries the cables to the ABC suspension at the rear of the wing passenger side, right where the wing vent sits, ok in theory any hot damp air from braking etc can rise into this duct. The SAM runs very hot, and it sweats

 

[Alex Crow]

i doubt very much that the sbc system is reliant on the front sams on either the 230 or211. to design it this way would be utterly ludicrous, and nonsensical (yes, sbc is a mistake, but no, MB were not THAT stupid).

a safety critical system like this will have as few external dependencies as possible. as an example the throttle position sensor for engine management is wired direct to the engine's ecu. just as the brake travel sensor on sbc systems must surely be wired to the sbc unit, esp controller will be on direct chassis can bus with sbc, and sbc will have permanent live etc so the sam should not stop it working at all.

malcolm, while you are in the mood for taking your life in your hands (under the controlled conditions you suggest), why no try it with the sams disconnected as well?

 

[television]

i doubt very much that the sbc system is reliant on the front sams on either the 230 or211. to design it this way would be utterly ludicrous, and nonsensical (yes, sbc is a mistake, but no, MB were not THAT stupid).

a safety critical system like this will have as few external dependencies as possible. as an example the throttle position sensor for engine management is wired direct to the engine's ecu. just as the brake travel sensor on sbc systems must surely be wired to the sbc unit, esp controller will be on direct chassis can bus with sbc, and sbc will have permanent live etc so the sam should not stop it working at all.

malcolm, while you are in the mood for taking your life in your hands (under the controlled conditions you suggest), why no try it with the sams disconnected as well?

Alex,,I have studied this in great detail,, the SBC pump is on the passenger SAM, and the drivers SAM,, there is nothing programmable in the pump or ECU,, the fact that you can turn of SBC in STAR does show that it is CAN controlled, and I know that it is.

The OP first post showed that after 1 hour the car found the brakes, this is the same as when mine went,, it took I hour to get to normal, there same thing on another car on here,, he borrowed a SAM from me to prove his 350 fault.

With the OP car they said "it lost a code" so the fact that it could lose a code is still valid,,It just so happens that I have been following these post on Both big USA forums as well re this SAM

The Passenger SAM cant be unplugged with ease as the starter battery has to come out and it a pig to get to it,,I cannot start the car with the drivers one out, so no go there and I had thought of it but dismissed it through the above reasons.

The point is then if not a SAM how can it be turned off and on in STAR and the car did lose contact with the SBC
There are some 30 components in the SBC system and sure I would love to be 100 right in the workings of it

 

[Alex Crow]

IF they have designed it to rely on more than the esp and sbc hydraulic unit then what a disaster! i still doubt they would make such an obvious gaff though, those engineers were not stupid.

 

[television]

OK please read page 24 what happens then when it does not wake up
http://www.mercedestechstore.com/pdfs/R230_adivsor/218 HO SBC (WJB) 09-30-02.pdf

 

[television]

I see that in an emergency the system meets the mandatory minimum deceleration of 0.3g with a pedal pressure of 500n (112 lb/ft)

Page 17

 

[television]

This one is for 211 owners
http://www.mercedestechstore.com/pdfs/W211_advisor/219 HO SBC (WJB) 9-30-02.pdf

Please note page 11

The whole system is as the 230 and if the SAM that has all of the wake up signals in it does not wake up (CAN controlled) then no SBC

 

[Alex Crow]

ok, the SBC unit has ALL relevent sensors/actuators wired direct - these include all the wheel speed sensors, the pedal value sensor, the brake light switch and the high pressure pump.

it has a standalone dedicated data bus with the esp(+sps and bas) module called the electrohydraulic brake can (can ehb) - this will mainly be sharing wheel speed etc with esp rather than the sbc relying on data from the esp to enable it's function of providing braking. WIS document gf42.50-p-5119ri makes it fairly obvious that this system has been designed to allow continued brake function from the sbc unit as long as it has its direct wired sensors (eg pedal travel) and a power supply.

corroded pins in the sam units will not cause brake failure, nor will sam units that are failing to function correctly. to design a system like this to rely on other modules would have been reckless, to say the least.

the sbc system is not on the chassis can (can-c), only on the ehb can with the esp module, which in turn is on the can-c. the sam units are on the body can (can-b), and share links with the can-c only through modules like the CGW. to suggest a sam unit failure of any description could cause sbc unit not to provide braking is way beyond any of the evidence in post #157, and not feasable according to how the system has been (carefully) designed.

re-reading post #157 we have no idea exactly what the garage were saying, where exactly this "missing code" was missing from, or even if it was in any way true. i suspect that actually they did know all about it (or rather MB knew all about it), that it has happened before, that it has been fixed, and that the explanation given was just bull.

 

[television]

ok, the SBC unit has ALL relevent sensors/actuators wired direct - these include all the wheel speed sensors, the pedal value sensor, the brake light switch and the high pressure pump.

it has a standalone dedicated data bus with the esp(+sps and bas) module called the electrohydraulic brake can (can ehb) - this will mainly be sharing wheel speed etc with esp rather than the sbc relying on data from the esp to enable it's function of providing braking. WIS document gf42.50-p-5119ri makes it fairly obvious that this system has been designed to allow continued brake function from the sbc unit as long as it has its direct wired sensors (eg pedal travel) and a power supply.

corroded pins in the sam units will not cause brake failure, nor will sam units that are failing to function correctly. to design a system like this to rely on other modules would have been reckless, to say the least.

the sbc system is not on the chassis can (can-c), only on the ehb can with the esp module, which in turn is on the can-c. the sam units are on the body can (can-b), and share links with the can-c only through modules like the CGW. to suggest a sam unit failure of any description could cause sbc unit not to provide braking is way beyond any of the evidence in post #157, and not feasable according to how the system has been (carefully) designed.

re-reading post #157 we have no idea exactly what the garage were saying, where exactly this "missing code" was missing from, or even if it was in any way true. i suspect that actually they did know all about it (or rather MB knew all about it), that it has happened before, that it has been fixed, and that the explanation given was just bull.

Well it is still on the wake up circuit, and if it does not wake up it cannot run.

It is not the corroded pins that cause the problem, the damage is enough to destroy the other side SAM and everything on the SAM's is lost. when these things happen all CAN circuits can be damaged