SL/R230: Stop- Brake Failure
Thread Starter
Senior Member
Joined: Apr 2007
Posts: 436
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Former R230, W220 and W221 owner
Stop- Brake Failure
2003 SL500- 92,000 miles
Jumped in the car, started her up and dash filled with red lights "Stop- Brake Failure". ESP and ABS lights on to. Turned the car off and the message and beeps were still on display. Turned the car back on and all normal
Luckily the Mercedes dealership is 3-4 miles away. After he checked my car in, he told me that the SBC is under warranty until 2028 and that they need to run diagnostics before replacing anything but all indications are that the SBC needs to be replaced. I'll find out Monday. I'm also reading that a low AUX battery could cause this. I admit- my car does sit for long periods and I randomly get "consumer battery offline" when starting the car after it ha sit for a while- I need to start hooking up the trickle charger
He said this was just a warning that its going bad- after so many brake cycles the thing begins to warn you....
Warn you? Seriously? By not braking at all? What's disturbing is that I've read you can lose all braking power at any moment when this thing goes south- people are pushing the brake pedal to the floor to get it to stop. This could be catastrophic. Imagine no brakes going 60MPH on the highway
Why hasn't Mercedes done an entire recall on the SBC? Why are they waiting for it to go bad? This could lead to injury or death. WTF mercedes?
Jumped in the car, started her up and dash filled with red lights "Stop- Brake Failure". ESP and ABS lights on to. Turned the car off and the message and beeps were still on display. Turned the car back on and all normal
Luckily the Mercedes dealership is 3-4 miles away. After he checked my car in, he told me that the SBC is under warranty until 2028 and that they need to run diagnostics before replacing anything but all indications are that the SBC needs to be replaced. I'll find out Monday. I'm also reading that a low AUX battery could cause this. I admit- my car does sit for long periods and I randomly get "consumer battery offline" when starting the car after it ha sit for a while- I need to start hooking up the trickle charger
He said this was just a warning that its going bad- after so many brake cycles the thing begins to warn you....
Warn you? Seriously? By not braking at all? What's disturbing is that I've read you can lose all braking power at any moment when this thing goes south- people are pushing the brake pedal to the floor to get it to stop. This could be catastrophic. Imagine no brakes going 60MPH on the highway
Why hasn't Mercedes done an entire recall on the SBC? Why are they waiting for it to go bad? This could lead to injury or death. WTF mercedes?
Last edited by imtheking; Nov 9, 2019 at 10:48 AM.
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Joined: Jan 2006
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From: Atlanta, unfortunately
'09 S600, (2) R129 300SLs, '03 SL500, '03 SL55
This fault message is a consequence of the car being equipped with SBC, but I don't think it is caused by the braking system. I think it relates to the voltage regulator output. A scan of the battery control module and SBC for codes would tell.
Thread Starter
Senior Member
Joined: Apr 2007
Posts: 436
Likes: 79
Former R230, W220 and W221 owner
Dealer called and said they will replace SBC under warranty- also stated the AUX battery is critically low and hasn't been replaced since 2014 which can also cause this error. Going to buy the battery and change it myself- dealer wanted $70 to replace battery- no thanks- takes 5 minutes
Banned
Joined: Jan 2006
Posts: 1,982
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From: Atlanta, unfortunately
'09 S600, (2) R129 300SLs, '03 SL500, '03 SL55
Last edited by bobterry99; Nov 11, 2019 at 11:34 AM.
Thread Starter
Senior Member
Joined: Apr 2007
Posts: 436
Likes: 79
Former R230, W220 and W221 owner
The fault is a consequence of SBC detecting a low voltage supply condition with the engine running. Most likely this is due to a failed voltage regulator or alternator, though in theory it could be due to a false voltage measurement. Only if the systems ("AUX") battery were physically damaged in such a way that it is loading-down the alternator below c. 10.5 volts could it be the cause.
I've been to lazy to hook up the trickle charger- actually the outlet is so far from the car, that I don't feel comfortable running a 50 foot extension cord down the front of the lawn to the back of the car. All I need is a mouse or some other rodent chewing on the wires and causing all kinds of other issues.
Banned
Joined: Jan 2006
Posts: 1,982
Likes: 393
From: Atlanta, unfortunately
'09 S600, (2) R129 300SLs, '03 SL500, '03 SL55
If "consumers offline" only comes on when the car has sat for longer than one week, then despite the systems battery being five years old it is likely working fine. If the dealer is replacing SBC, then I'd see how matters are once that is completed.
