Hello everyone, Ok first let me start off by saying that I know how many threads have been posted that are similar to this but I just need a clear answer and I have been reading different things.

I replaced my front pads, rotors and sensors yesterday. There was a RED BRAKE light in the FSS for about a month and a half before I replaced the parts (Money Issues). The message reads like this: BRAKE Reduced braking effect start engine! this is when the car is off with no key in the ignition, this light comes on as soon as i unlock the car before i even get in it you can see the light through the window.

My question is this: Could it be the SBC Pump that failed and needs to be replaced? I have read on other threads that Mercedes has an extended warranty on this unit for 10 years/unlimited mileage .

When I replaced the parts, I did not unhook the SBC unit because I did not know I had to do that . Everything was done correctly and I tried resetting the light with a scan tool also but no luck, the light remains. The brake pedal also goes pretty far down compared to when i first got the car. Any help with this and what I have to do to get rid of that light would be greatly appreciated. Thanks. Oh it's a 2003 E500 by the way.

 

Disconnecting the booster during service is a safety precaution. It can start without notice and it is reported that it could crush your fingers. I think the SBC failure message is different and more frightening than what you have displayed. It is incredible (if true) that the SBC becomes inoperative once it reaches a preset count (ie 350,000 cycles?) . Apparently this comes without warning. I have seen a FEW posts about people resetting them. Obviously Bosch felt strongly enough about the life cycle of the unit to program this feature into it. The Europeans have more experience with these things but several people on this board have had sudden failures that scared them, prompting some pretty unkind remarks. I think the whole design is a candidate for Engineering Disasters on the History Channel. You can certainly have it checked by a dealer, if it is defective, I believe M-B will step up with a new unit. I think that braking is so poor without the booster, it would be evident immediately. Somewhere a bunch of lawyers are getting ready. As these cars age, this is going to become a real service issue. Sorry, I cannot offer more.

 

I had, what turned out to be, a combination of a bad brake switch and an SBC pump that was timed-out. The combination of the faults caused the red message. When I fixed the brake switch, I then just got a "Brake - Visit Workshop" message. The SBC pump was replaced under the 10-year warranty converage and no messages at all.

 

BRAKE Reduced braking effect start engine!

What an odd message to post when the car is obviously too dangerous to drive, a better message would be "exit vehicle and run for your life"

 

Well I did also get the regular BRAKE - visit workshop message in the normal blue color before i got the red message and I replaced the brake switch but it never went away... So you think it could be the SBC pump?

 

The only way to know for sure is to have an independent shop (or dealer $) read the fault code. If your car is older, has lots of miles and did lots of stop and go driving, then there is a good chance the pedal activation threshold has been reached. The car, in my case, still stopped fine. The computer just required the SBC pump to be changed and now all is fine.

 

I just went through the same problem (red brake light ) couple of days ago and it drove me nuts. But then I retraced my steps, double check everything and eventually it went away. Since you’re mentioning that your brake pedal is spongy, I would probably suspect air bubbles in the line. Bleed the system first, but it may not work the old way pressing on the brake pedal. You have to force it thru with slight pressure thru the fluid reservoir. Basically, you pressurized the system and open the bleeding screw (make sure you have enough fluid in reservoir). There are kits out there that you can buy to do this or in my case, I just rigged it up in my garage. Another scenario, it is your SBC pump or brake light switch. You would have to physically test the switch for continuity, press and release. I believe the faulty sensors will only throw message “ Visit Workshop”. In my case it was air in line and after I bled the system everything was fine. If everything fails you may have to take somewhere to read the codes.
Good luck. Jan

 

I recently had the SBC pump replaced by the *******s at Fields BMW/Mercedes in Lakeland, FL. The techs and mangers there are real tools, but thats another discussion all together.

I got my car back, never to return there again, and have had several issues. This latest one is a Brake Light warning on my dashboad that doesnt go away along with this alarm/chime that goes off every time I hit the gas.

I checked the fluid, fine. I ran my icar software to reset the brake but it fails every time.

The headlight wires burnt out and now they wont turn off unless I remove key, and drains my battery if I dont unplug it over night. Was wondering if I could just buy an HID kit, but dont know where to plug the ballast into because of how the wiring is.

Replaced the small annoying white piece that raises and moves the steering but now that doesnt work, radio out, trunk release out, tag lights out (getting power but very low. Ithink it was 2.5) and seats out... all at the same time, but fuses are good (top on driver side panel but cant locate the trunk release fuse).

I know Im going to have to buy the $34 kit to rewire my headlights, but im not looking forward to ripping it all apart and rerouting the wire.

I need to locate the drain so I can stop unplugging the battery. So if anyone can assist with that?

I have very little tools atm but I do have a DMM, but its not a fluke so... its limited...

I attached a pic of the dash..

I tried BTS by watching youtube videos but seems to be diffetent issue with my car because I dont hear chimes and nothing worked because the display never changes. Just the brake warning.

Beside the electric issues the car runs great. No problems accelerating or stopping.. no low beams, only high until I get kit done... ppl hate me...

 

Is your small battery under the hood in good shape? I had the same issue on my 2003 E320. The auxiliary battery under the hood, the smaller of the two batteries on the car, was bad. I replaced this battery, and all worked fine thereafter. I suggest you check this, as it would be a cheap start to possibly fixing this problem.

 

When the auxiliary battery goes bad it can make all kinds of weird **** happen.

 

small battery is good...