NuBenz

I understand that the Sensotronic Braking System has a full hydraulic back-up in place in the event of electronic failure or electrical system malfunction.

1. Anyone know how this hydraulic system is allowed to function in the face of Sensotronic failure? Under what circumstances will the electronics be overidden by the mechanical/hydraulic system?

2. If battery power is lost (e.g. dead battery, or simple disconnect), will this actually disable the ignition once power is restored (meaning I won't be able to start the car)? And do the Sensotronic brakes need to be "reset" at the dealer?

Please fill me in... thanks!

bmms8

nice questions, i cant answer anyone of them, sorry, but there is a back up battery, if anything happens

jim256

I'd like to see a detailed technical explanation, too, but the hydraulic system as described in the manual references that it only operates on the front brakes, that additional pedal travel and force would be required, and that stopping distances are longer.

I suppose pedal travel, alone, could engage the hydraulic backup in the event there was no reaction to initial pedal application via the electronics. There's nothing I see in the manual to say that battery disconnect or failure affects the safety systems.

Otto

NuBenz,

for question 2, after you get a jump start for your dead battery, you have to go back to service to reset your sbs in order to make it work properly. at the mean time, the break system still works but you may press your pedal harder.

for question 1, if your electricity power below certain level, you can use mechanical/hydraulic to take over sbs but again you better visit a service center soon for your own safety.

actually, if your battery electricity goes below to a certain level, you cannot start your car -- your key stays in position 0 which protects you to drive car without sbs. (a jump start or battery replacement can fix it but after that you will see a sbs malfunction shows up in your menu)

dead battery is NOT equal to disconect battery as I known for the new e. the former you have to reset sbs and other setting after you get a jump start or replace a new battery; the latter, you only need to resynchronize your 4 windows and roof. when you disconnect your battery means you disconnect the one in the trunk and only disconnect the negative cable.

Otto

abhansali

just out of curiousity, does this mean that if my battery goes dead, not only do I have to buy a new battery from a store, but I may have to pay a nice little service fee to the dealer to get my brakes reset?

Frankly speaking, every car I have owned, I have rarely taken it to the dealer for service, because they charge an "arm and a leg" for something any other service shop can do. But it looks like this MB could end up racking up big bills for service...

NuBenz

These electronics are really, really complex. The W211's owner manual must be 500 pages! With 300 of those pages about electronics! :p I would be very interested in learning about how the hydraulic system in the brakes is actuated, especially since braking is such a vital part of safe driving.

So, there is a backup battery in the trunk for maintaining power to the computer goods?

Merry Christmas, everyone!

Cheers!

Otto

NuBenz,

I am learning all hiden/undocumented features, too. I would like to share whatever I learned with everyone here.

Otto

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abhansali,

if you mb battery dead but it is under warranty then you will get a free one with free reset settings but after 4 years/50000 miles warranty expires (assume you do not buy the extended warranty then you have to pay the battery and the reset fee; however, most of the battery runs dead after warranty expires.)

That is why I sugguest you get a trickle charger from mb -- it costs between 70 to 90 bucks according to the one from my bimmer. the trickle charger can make sure your battery always on the best condition which makes your battery last longer. by the way, it is very easy to use the trickle charger, just plug it into your ac and let it charge overnight every 2 weeks or every month. it depends on how you use your car. the best of all, you can have a long vacation without worrying the dead battery. (Our local mb dealer charges $65 bucks per hour for labor, so trickle charger can save you more after your warranty expires)

Otto

Otto

Otto

NuBenz,

I forgot answering your question,

there are two batteries, one in front, one in the trunk, the former is the auxiliary one, the latter is the main one which provides the power to start engine. if you lose the power of the main one, you have to reset the following settings according to the user manual

1. set the clock, page 136.
2. resynchronize the front seat head restraints, page 104.
3. resynchronize the esp, page 75.
4. re-enter the radio code.
5. resynchronize the side windows, page 186.
6. resynchronze the sliding/pop-up roof, page 189.

I believe we can do them all by ourselves but if you lose the power in both batteries, then you have to go back to service center to reset more stuffs. e.g. SBC, etc. the brake still works but you have press the padel harder and do not drive more than 55 mph because of your brake.

Otto

NuBenz

Thanks, Otto!

I'm learning so much more about this car from owners like yourself. I hope in a few months we'll be in a Gremlin-free E500!

Regarding the MB trickle charger... as I understand it, there is no unit available yet. Porsche has one as do many other european manufacturers. If you lose power in the 996, you need to hook up the trickle charger to the cig lighter outlet to provide just enough power to "pop" the electronic latches to the engine bay and boot for a definitive jump start.

An alternative is to hook up the jumper battery to the fuse box, which has a terminal for temporary power to "pop" the latches. Older 996s had cables for mechanical unlatching in the event of power failure.

Merry Christmas and ENJOY THE RIDE!