Good morning all - MB World newbie here, from (near to) London, England. When my car - an '03 E55 Wagon - had its annual Government safety check recently, there was an advisory for front brake pads (4mm left). The pad wear warning hasn't come on yet, but I suspect it won't be long before it does. I'll change them this summer, while the weather is good.

The car has SBC. While I'm changing the pads I really don't want the SBC to wake up and eat my fingers - I'm very attached to them...

There's a procedure in the new Haynes W211 manual for deactivating and reactivating the SBC system, and I found a rather simpler one on this website, as follows:

1. Close all doors.
2. Wait until system is asleep ( Instrument cluster will go completely black)
3. YOU CAN NOW WORK ON THE BRAKES, BUT DO NOT ‘WAKE UP’ THE SYSTEM BY LOCKING OR UNLOCKING THE CAR OR OPENING A DOOR!!!
4. ONCE DONE, START THE CAR AND PUMP THE PEDAL.
5. IF THE RED LIGHT COMES ON, CYCLE THE KEY SEVERAL TIMES UNTIL IT EXTINGUISHES.

However, the Haynes manual also states that the system can be de-activated simply by disconnecting the main battery and waiting ten minutes. That's simple, and I like simple; simple is best - less to go wrong.

Even simpler, would be to disconnect the SBC unit from the car's electrics, but I assume this will not work. First question: am I right?

The actual pad change, except that there are four (?) pads on each wheel, not two, seems just like any other pad change; I've done hundreds of them down the years, so should not be a problem - or (second question) might it? Is there anything I'm missing?

Finally, (third question) if disconnecting the SBC unit is a non-starter, do I risk screwing up anything else by disconnecting the main battery?

Any and all advice gratefully received.

E55BOF

 

there is usually a second, motorcycle size battery under the bonnet on my 2005 e280, this i believe also powers sbc.
However, this is what mercedes manual says to disable sbc without Star diagnostic machine, see attachment file.

 

Thank you for that, Diverzeusy. That's the procedure in the Haynes manual, but I'm intrigued by the Haynes statement that SBC can be deactivated simply by disconnecting the main battery. Does anyone know for sure that this is right - or wrong?

 

I've just changed my front pads following Mercedes, without 'star' method, all went well.
Regarding the battery under bonnet, I have read about it powering SBC on here somewhere, but can't remember where.
Just follow merc/ Haynes way, and don't put fingers inside caliper! Just in case, also push old pads ' back' in situ, to force pistons into caliper, that way if it ' wakes up' no dramas.

 

Thank you, gentlemen. No answer on simply disconnecting the main battery, so I'll go with the procedure I already have. One further (two-part) question, though, if I may. With the bonnet open so that I can syphon out excess brake fluid from the reservoir, can I lock the car with the remote to make absolutely sure I cannot have a senior moment and absent-mindedly open a door? And if I should absent-mindedly close the bonnet while the car is locked, will this awaken the SBC?

 

you shouldn't need to syphon any fluid off as the level will have very slightly dropped as the pads wore away, so you are merely pushing the same fluid back, to where it started bafew thousnd miles ago.
as for opening doors, just put some masking tape over the handles to remind yourself, and keep the bonnet closed, there is no need to open it, and it may wake the 'finger eating devil

 

The fluid's on the full mark now, so it must have been topped up since the pads were last replaced. I'll keep an eye on it as I do the job.