Dave3359

Hi all looking for some HELP just did a complete brake job on my 2007 sl550
As soon as I started the car I got abs light with reduced power to the car any thought

Plutoe

Now you are screwed and will require factory software to interrogate the module and clear the fault---no your homie OBD reader will not work!!

Heatwave

Dave3359: Did you get your brake problems sorted?

You say you did "a complete brake job." What all did that entail? Pads? Rotors? Brake bleed?

Did you disable SBC before you began your work?

What was the problem and how did you get it resolved?

I am going to replace pads and rotors on my R230 in the next coupla weeks. I'm trying to learn from others.

Dave3359

Hi Heatwave
Yes I did do a complete brake job. All new rotors (Zimmerman) Akebono pads and I replaced all the hardware clips and retaining pins. I tried to disable the SBC unit but wasn't sure how to after I did the brakes got red light ABS warning and car went into limp mode car. Called my Indy made an appointment to have him put it on the SDS but the next day tried the car again and everything was back to normal? Still had him put it on the SDS and the code said SBC unit had a glitch and reset itself. And while it was there he did a brake flush. Maybe someone can explain how to disable the SBC unit so we can all benefit

Rudeney

SDS, go into Control units -> Chassis -> SBC -> Deactivate System SBC. Once work is completed, go choose "Activate System SBC". You will be prompted for what work was performed. Choose "maintenance" and then "replace brake discs". Do this regardless of what you replaced as this does a proper calibration.

Some people w/o SDS will just unplug the electrical connector from the SBC unit, but that does not relieve pressure, it just keep the pump from running. You need pressure relieved so that you can safely work on the brakes without damaging them or yourself.

Heatwave

Rodney: Thanks for that good advice.

Question: after deactivating SBC but before starting the rotor replacement work, should the brake reservoir be uncapped and should a quantity of fluid be removed from the reservoir? (And replaced after the work is completed, of course).

Dave3359

Hi Rodney here are a couple of photos of my SBC unit can you please explain to me how to unplug this. I don't see how with out Breaking anything thanks Dave

Rudeney

There is a way to "manually" deactivate SBC:

http://benzbits.com/r230/DeactivateSBC.pdf


Like I said, don't try to unplug it - that does not release pressure on the system, it only keeps it from re-pressurizing.

Dave3359

Hey Rodney in your previous statement you said just unplug the electrical connector on the SBC unit is that doable? I understand that it doesn't relieve the pressure on the brake system but it isolates the SBC unit correct? I'm trying to understand if this can be done unplugging the SBc unit thanks again for all your efforts and your knowledge I greatly appreciate it Dave

Rudeney

I said, "some people" do that and I also said would not do that as it does not relieve pressure. It could be like trying to work on the brakes while someone sat in your car with their foot on the pedal. It's imperative to properly discharge pressure AND deactivate SBC before working on the brakes.

Heatwave

Rodney: you posted, "It's imperative to properly discharge pressure AND deactivate SBC before working on the brakes."

Are those two separate and necessary actions? Or does deactivating SBC discharge pressures?

I know how to deactivate SBC using SDS, but "discharging pressures" ... I don't know about that.

Rudeney

Yes, when you use SDS (or, presumably, that "W/O SDS" procedure I linked), this also d-pressurizes the system.

You know the humming sounds you hear when you open a door, or step on the brake before starting the engine? That's the SBC pump operating to pressurize the system. It also does this periodically as you drive, but you won't hear it with the engine (and radio) running. That's the "finite" lifespan part of SBC that can only happen 300,000 times before the pump must be replaced. It's not 300,000 brakings - it's 300,000 pump runs. One pump run can provide dozens of brakings, depending on conditions.

The SBC system is actually more than just an electric pump in place of a pneumatic booster. It can measure the pressure on each brake caliper so that it knows the position of the pads relative to the rotors. It can apply the brakes for you without you pressing the pedal. of course this happens with the ESP/BAS system, but it also does this when the wipers are on (to dry the brakes) and will even move the pads close to the rotors the moment you lift your foot from the accelerator - closer when you lift your foot off very quickly as if you are about to slam on the brakes.

Here's some interesting reading. This is for the MY2009 refinement, but it mostly applies to all SBC-equipped cars (I think the brake hold features was not added until MY2009, and it's not available int he USA anyhow):

http://benzbits.com/r230/SBC_Functions.pdf

Heatwave

Thank you for the explanation and for the link. I've printed the link and will read it later today. FYI ... my '07 R230 has a hill-hold brake effect.

I plan on replacing all my car's rotors and pads within the next week or so. I will disable the system with SDS before starting work. Your posts have informed me greatly about my car's brake system and the perils of working on it, and I thank you.

PS. While using SDS several months ago, I changed my "car nationality" to something other than USA ... maybe Germany or Switzerland. Doing so enabled me to activate the flashing brake light feature. I think it also enabled the hill-hold feature ... earlier my car did not have hill-hold, but it has since changing nationality. Go figger.

Dave3359

Ok I understand everything you're saying I got it. My question is HOW DO YOU UNPLUG THE SBC connector that's what I'm looking for thanks again for your support and Patience

Rudeney

I really don't know how to unplug it. I'd have to look at the connector to see what type of locking system it uses. I'm at the beach this week, and we don;t take my car (wife won't ride in it for the 4 hour trip), so I'll have to check when we get back next week.

Dave3359

Thanks again Rodney ok enjoy your beach time and relax I did post photos in post #7 I don't know if that helps? Thanks again for the info

Heatwave

Rodney: I hope your beach time wasn't ruined by the tropical storm that delivered half of the Gulf of Mexico's water to the Southern US states.

Anyhow ... I followed your advice regarding deactivating and later reactivating SBC via SDS. Everything worked perfectly. Many many thanks for that sound advice. The hardest part about the SBC/SDS work was dragging out the ancient Dell laptop, the multiplexer, the wires and cables, the power cord, and getting it all set up, then unplugging everything and packing it properly in the storage case.

Deactivating SBC was a piece of cake: select an option on the SDS screen and it's done. Reactivating was illuminating ... listening to the SBC system cycle through its steps in restoring balanced pressure to the brake lines, and seeing the four-brake results on the laptop screen gave me a great appreciation of the importance of deactivating/reactivating the brake system via SDS.

I replaced only the rear rotors/pads yesterday. The front brakes will have to wait a few weeks ... it takes more time now for my old body to recuperate from an afternoon of lying on my back and trying to generate enough torque on a wrench to turn damn tight brake bolts. I sure wish I had a garage lift.

Thank you for your insistence on deactivating/reactivating MB brakes via SDS. I'm a true believer now.

Rudeney

I'm glad all that worked out for you. Once you get used to using SDS, it's not so bad. I keep my old Dell D630 in the garage, plugged into its docking station and "sleeping". My multiplexer cables are long enough to reach the car while it sits there on the counter.

As for the beach, we did have some weather from TS Cindy. We got to Destin on Monday and it was overcast. Tuesday and Wednesday were very rainy and windy, but that's OK as I had some maintenance things to do around the condo - my niece's husband installed a new cable box and now the programmable remote doesn't work it, so I had to fiddle with that. Plus a curtain rod broke. We don't actually go to the "beach" - my wife will not get in the ocean and we really don't care much for sand. We just like being there to relax, hang out at the pool (me mostly - she's decided she does not need the sun), and eat some fresh seafood. Thursday ended up better - at least no rain, but Friday was beautiful. We were coming home Saturday, but stayed until today (Sunday) since it was so nice.

Dave3359

Hi Rodney hope you had a relaxing time at the beach. Was wondering if you had time to look at the SBC plug on how to unplug it? Thanks Dave

Rudeney

Sorry, Dave, I totally forgot! It's actually very easy. I was fairly certain I knew the solution, but wanted to put my hands on it to verify. All you do is pull straight up on the part shown below. It even has indentations on the sides for finger grips. It will lift easily about half an inch, then you have to pull harder to get it to release the connector. You'll see the connector begin to move away from the unit as you lift. There is a gasket on it to keep out the elements, so I'd clean and re-grease it before reconnecting.

Please keep in mind that while this will disable the pump motor and keep SBC from cycling or operating the brakes, it DOES NOT relieve any pressure already in the system. You should not rely on this as a substitute to properly disabling SBC when servicing! Also, after replacing brake components, it is necessary to have the SBC system recalibrate itself, which only happens if it was properly disabled.

Dave3359

Thank you for all your help. It's just good to know how things work

Frederick NL

Rudeney, I used that instruction for my 240.467 (2005) and it all works as described, including the FL wheel locking up, but the final three-blinks-finale (self test completed) never shows up. Any guess why..?

(As a side note, my LR brake disc is running hot, since all discs, shoes and parking brake shoes were replaced, so we're looking for a reason, perhaps the parking brake needs simple adjustment).