willscam

So yesterday, I'm casually driving home from work doing about 40mph on a surface street, when suddenly the dash lights up flashing a red warning - brake failure - stop immediately - visit workshop - increased braking distance, etc. My car starts automatically dropping into lower and lower gears. As I approach a stoplight at maybe 10mph, I step on the brake. There is no resistance all the way to the floor! I use the emergency brake to come to a stop before hitting a vehicle stopped at the light in front of me. When the light turns green, I slowly - very slowly- pull into a gas station at the intersection and use the parking brake, again, to stop. Thinking it's probably something computer related, I turn off the car - wait a few seconds - and then start it back up. The warning lights went away and my brakes came back. I drove home cautiously - a couple of miles- and the brakes worked without issue the entire way. Nerve rattling to say the least. I'll take my car to the dealership today - only 2 miles from my house. I've printed the service campaigns regarding SBC for the service manager. I don't have alot of trust in the service department though. Shortly after I bought the used car, about a year ago, the car developed some electrical issues and the dealership replaced the alternator. At that time, I asked if all the recalls and campaigns had been performed on the car and they assured me that they had. I'll post again with the results from the dealership visit.

Diesel Benz

It would have been nice to have a photo from the SBC pump before the workshop visit, one could have seen if the car had the recall work done for the wiring harness.

The electrical issues should not have appeared if the corresponding recall fix had been done, at least it should have been unlikely.

Seems you did not panic as you figured out to use the parking brakes. Sounds odd if it did not brake at all first but was functional after off/on. Also the brake pedal should not behave differently if SBC brakes work or not, the pedal has a simulated force when the pedal is pressed. Perhaps you mean you did press the pedal with good force, not just with low force, making it go fully down. The pedal should have a "mechanical" backup, the braking force would be low relative to the pedal pressing force but it sounds like you did not feel the backup system braking at all? Perhaps pumping the pedal would have helped but I understand you did not have too much time to try that.

MB Fanatic

tell them to reset the counter on the sbc pump. your brakes will start working fine once again.

Diesel Benz

Can you tell more about this. I doubt the brakes were designed to stop working once the counter hits the specified number. You will get rid of a service warning but this was a different case in my opinion.

Scambo

Sounds like a possible issue with the Battery Control Module (BCM) to me...This is not an isolated event, as it has happend to a number of us.

willscam

I didn't get a chance to take the car in on Saturday as I had to work. Service is only open 8:00am to 1pm on Saturday. My plan is to take it in when they open on Monday. I also printed out the campaign regarding the battery control module, as Scambo mentioned, and my research suggests, that could be a possible cause of the brake failure.

Diesel Benz

BCM or the alternator regulator? But both should have been covered by recalls.

Diesel Benz

If the car after all did not visit an MB workshop yet, could you take a photo from the SBC pump, covering the connector and the cable near by the pump (assuming you would be interested about the recall work being done for the pump wiring).

vettdvr

Total brake failure for any reason,, electrical or not is totally unacceptable.

This happened to me also. I had the car towed to MB. Complete sbc system was replaced. I also filed with NTSB as safety issue for them to follow up and track frequency.

Diesel Benz

Sure it is absolutely unacceptable. But I'm still curious if the failure was absolutely total, sounds odd if the back-up system too fails. Perhaps the failure on the SBC side left the control valves to a position where the back-up system pressure did not reach the wheels? Can you confirm that in your case there was not even any reduced braking power from the back-up system?

MB211

The back up was probably there....it just does not feel like it because pedal is very soft. The soft pedal leads to panic, leads to depressing parking brake and not even knowing if hydrolic brakes worked.

Diesel Benz

Thanks, as I mentioned earlier, after the panic from brake malfunction, I'm afraid not all would even realise they could/should use the parking brake. Seems at least two drivers have been cool and clever at the incidence.

vettdvr

If there was any back up my wife could not find it. She was fortunate enough to be able to drive off the side of the road and coast to a stop. She shut the car off, then restarted, the SBC BRAKE FAILURE warning went off and she drove 3 miles home. (we won't go there about wives reading the instructions). I got in the car started it put it in gear, and all the red bail out brake alarms went off. Since I could not find the black and Yellow hashed handles to eject I called a tow truck. The dealer replaced the SBC system and the system has been fine since then.

My job as customer was not to try and find the root cause failure analysis on the brake system. When MB decided to go with FBW these problems belong to them.

Now as an engineer I would like to know what failed, but I won't spend my time against finding the cause. That's MB's work.

Diesel Benz

I agree with the above but I'm sure too MB has already figured out the issue but I'm equally sure they would not tell us much about the details. As an engineer and an MB enthusiast, I would like to know more even if I've never experienced anything like that on my cars. Gathering info from the forums is often the only way get up-to-date with the issues.

willscam

My SA called yesterday and left a message. He said that "somebody put DOT 5 brake fluid in the car instead of DOT 4" and that was what was causing the brake failure - bubbles in the hoses, or something to that effect. They are denying the warranty coverage for that reason. They estimate repairs at $4K. I returned his message, telling him that I had not changed the brake fluid myself, but I bought the car used from Carmax about a year and a half ago and would take it to them. I have an extended warranty through Carmax, so hopefully this will get resolved without elevating my blood pressure too much. When I pick up the car from MB, I will request a written explanation for the warranty denial. I'd like some evidence that there is DOT 5 brake fluid in the car.

vettdvr

Best of luck to you. Don't know how they could tell Dot5 vs Dot4 MB brake fluid. But if you had Dot 5 it very well could be the cause. I dont' understand why the cost would be so high. I would try to full flush the fluid refill with Dot 4+ as per MB and then verify.

If the Dot 5 caused seals etc to be damaged then you would have a more extensive repair. But I would try the total brake system flush before throwing the baby with the bath water.

FYI it is very possible someone did put Dot 5 in the brake system. I just picked up my diesel truck from the shop that installed a new transmission. This truck uses Mercon III fluid in the powersteering system and brake booster. The pump was screaming at me when I picked it. I checked and the cap was off the pump. At home I did a full flush on the system with the correct fluid and the noise stopped and the system began to function normal. MY guess someone put power steering fluid in the PS pump that requires Mercon III. So if this could happen to my truck I can also see Dot 5 in your brakes. Best of luck and don't be suprised if Carmax denies it also.

gnma

If I understand this, was your car was at the MB dealer the LAST time it was serviced? If so AND they stated all recalls/campaigns had been performed, and now they're telling you you have the wrong fluid in the brake system, well, isn't it their fault??

I imagine when an MB comes into the dealer, they make sure the car is up to par in terms of recalls, esp. the SBC system? I don't think they wait for the car's brakes to fail and then repair it free?

willscam

Picked up car from MB today. They said they could tell it was DOT 5 by the purple color. DOT 5 should not be used with ABS b/c of tendency to aerate in small orifices. Tech notes from paperwork states "short test, found several SBC hydraulic failures, no leaks found. Checked brake fluid, found DOT 5 brake fluid installed, causing hydraulic failure in SBC unit. recommend SBC unit, brake operating unit, and multiple brake flushes to restore brake system to DOT 4+. Customer declined repair."
At Carmax, I spend 10 minutes explaining the situation with the service guy. I get a blank stare when I mention SBC. They're busy, so they're going to send my car to an independent shop "Norm Baker". After I leave Carmax, I look at the repair order. One line - "Brake failure lights come on". Oh well...I'll try to explain things to Norm Baker. Maybe they can test the brake fluid to see if it truly is silicone based (DOT 5) rather than glycol (DOT 4). I've use Ate super blue DOT 4 in my BMW (again, haven't touched the Mercedes brake fluid) and the color is just dye.

vettdvr

FYI,, If I remember correctly DOT 4 + is what is used in SBC not just DOT 4. There is a difference.

willscam

Yeah, you're right. DOT 4+ is what's mentioned in the tech note.

willscam

I just received a call from Norm Baker. They said a modulator valve in the SBC is stuck and that is what's causing the problem. They're going to have to replace the SBC unit, which is about $4K, but it will be covered by the Carmax extended warranty. I asked them if they found DOT 5 brake fluid. They said the brake fluid is fine, DOT 4+. They also found severely worn motor mounts that they'll replace while they're in there - also under warranty.

So, I've learned two things. 1) Extended warranty is a worthwhile investment from Carmax. 2) Never do business with Fletcher-Jones in Las Vegas. That's assuming they were BSing me - a pretty safe assumption.

I've had the car for 1 1/2 years and put on 5,000 miles (car now has 27,000 mi) and I've had the following repairs - which Carmax has covered under Maxcare extended warranty:

1) alternator/ fuel pump - $ 740 parts/labor
2) replaced combi switch (windshield wiper problem) - $ 332
3) SBC malfunction ~ $4000

After deductibles, I'm out about $200, instead of $5000.

konigstiger

Request a detailed invoice for repair inclusive of statement confirming brake fluid is correct. Reasoning is two fold, first to alert Fletcher (see below) and second to reference for future repair (SBC is covered by MBUSA for ten years/unlimited mileage) if needed.

MR. TOM DOWNER, COO
FLETCHER JONES MANAGEMENT GROUP, INC.
7300 W SAHARA AVE
LAS VEGAS, NV 89117-2756

K-A

I am not a fan of F.J Las Vegas at all. They have 2 Service branches in L.V, I called for ABC Fluid for my S500 once, they quoted a price of $22 or somthing at one (normal price), the other (closer to me) quoted $60 something, then when I told the guy the other quoted me $22, he says "oh sorry, I made a mistake, it's $22)

Then I go there, a new guy's behind the counter, and wants to charge me $60 something, I tell him the story and he refuses to call the other branch and says they might be quoted me wholesale prices....WHY would they do that? Angered me so much. It's like when you're dealing with such incompetence, you're just so powerless in the situation.

Anyway, congrats on getting it fixed for cheap. I just don't like the way F.J L.V seem to do business.

willscam

So, to close the loop on this... I got my car back from Norm Baker Motor Co this afternoon. A certified Mercedes-Benz mechanic worked on the car. The repair invoice states they "replaced modulator valve and verified operating as designed" - Parts, tax, labor = $1810.75. They also replaced worn motor and transmission mounts - Total = $619.07. Grand total for repairs = $2379.82. With Carmax extended warranty, I just paid the $50 deductible. They didn't put in the invoice that DOT 5 was not found in the braking system. Even so, I'm still planning on writing Fletcher-Jones to convey my displeasure. Maybe they'll reimburse my diagnostics charge, though I'm not going to hold my breath. The car is running fine - for the moment. I'm not concerned though. If the brakes should malfunction again, it will still be covered by the Carmax 6yr/ 60K mile warranty. I will definitely be out of this car before the warranty expires.

vettdvr

Good plan,, Glad you had it all settled