SL/R230: SBC light.
Thread Starter
Junior Member
Joined: Dec 2017
Posts: 62
Likes: 10
From: England
R230 SL500 W211 E220
SBC light.
Hi all
Quick question about sbc. The last couple times when i've started the car after sitting for 2 or 3 weeks the reduced brake comes up in red then goes out. In the malfunction there is nothing & the car is fine no warnings lights. Could that be it's on it's way to failing or maybe the battery being a little low. I do have a trickle charger running on it though.
Thanks
Quick question about sbc. The last couple times when i've started the car after sitting for 2 or 3 weeks the reduced brake comes up in red then goes out. In the malfunction there is nothing & the car is fine no warnings lights. Could that be it's on it's way to failing or maybe the battery being a little low. I do have a trickle charger running on it though.
Thanks
Banned
Joined: Jan 2006
Posts: 1,982
Likes: 393
From: Atlanta, unfortunately
'09 S600, (2) R129 300SLs, '03 SL500, '03 SL55
I speculate that when the SBC control unit gets the engine running signal from the alternator by way of the passenger-side SAM module it detects a voltage powering it is below 10.5 VDC just for the brief time you see the fault message. I don't think the state of charge of the rear battery could cause this, though as an experiment you could start the engine with the rear battery disconnected and see if no message appears.
Apart from the above, Colin, I won't speculate any further.
Apart from the above, Colin, I won't speculate any further.
Thread Starter
Junior Member
Joined: Dec 2017
Posts: 62
Likes: 10
From: England
R230 SL500 W211 E220
I speculate that when the SBC control unit gets the engine running signal from the alternator by way of the passenger-side SAM module it detects a voltage powering it is below 10.5 VDC just for the brief time you see the fault message. I don't think the state of charge of the rear battery could cause this, though as an experiment you could start the engine with the rear battery disconnected and see if no message appears.
Apart from the above, Colin, I won't speculate any further.
Apart from the above, Colin, I won't speculate any further.
Member
Joined: Sep 2019
Posts: 230
Likes: 87
From: Northwich
R230 350SL
When my convenience battery was running very low this was one of the symptoms I experienced. If it’s just momentary I wouldn’t worry about it, but in my case I didn’t understand the way the battery can discharge if the car isn’t running often. Consequently the car went into a default brake mode where I had to press the pedal harder to use the brakes. I only discovered this when I sorted the battery and started trickle charging it when the car was parked. Then I interrogated stored fault codes and found one relating to brake effort. When I cleared all codes the brakes restored and when I drove the car next, it felt like I had new brakes lol.
Senior Member
Joined: Apr 2007
Posts: 436
Likes: 79
Former R230, W220 and W221 owner
I think they extended the warranty on the SBC to 25 years, unlimited miles?
Low consumer can cause this issue but since its covered under warranty, take it to the dealer and have them diagnose. No brakes at 50MPH is no fun and dangerous. Get it replaced
Low consumer can cause this issue but since its covered under warranty, take it to the dealer and have them diagnose. No brakes at 50MPH is no fun and dangerous. Get it replaced
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Thread Starter
Junior Member
Joined: Dec 2017
Posts: 62
Likes: 10
From: England
R230 SL500 W211 E220
The warranty isn't covered here in England.
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