Mercedes-Benz Forum banner

1 - 9 of 9 Posts

·
Registered
Current: '07 SL550, '06 ML350 - Past: '99 ML320 (Sold), '98 SLK230 (Wrecked), 05 SL500 (Wrecked)
Joined
·
377 Posts
Discussion Starter #1
This morning I got in the car (07 SL550), started it and drove 2 blocks, when a red warning came up about Brake, reduced effect depress pedal fully, Drive to shop.etc. Sure enough the braking was minimal, and had to press the pedal quite a ways before it stopped the car. It's a good thing I was only driving 25-30mph.

Anyway, turned the car around, and went home, and put the iCarSoft MBII reader on it. for some reason, whenever I would try to read the SBC section, I would get an error that it couldn't communicate with the module. I could communicate with everything else, just not the SBC.

Meanwhile I could hear like pumps or electrical motors going under the hood, even though the engine was off albeit the ignition was on. About 30-60 seconds later, the noises stopped, and the error on the dash went away. I turned the car off, then back on, and all the problems are now gone (at least for now). I still can't get a response from the SBC module, but the brakes work fine, and there are no DTC anywhere else, other than some stored AAC errors from when I forgot to plug the SC contrl module in the center console.

So, this was very similar to the behaviour I had when my old SL500 had the SBC go bad, but this time there were no SBC error on the dash, only ABS, and I think I saw also ESP for a moment. I wish I had take a snapshot of the dash but I didn't.

So what could have happened, and should I take the car in to have the brake system checked? Why can't the iCarSoft MBII communicate with the SBC module?
 

·
Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
Joined
·
18,991 Posts
I'm not sure about the iCarsoft issues. That could be the iCarsoft is faulty or maybe the SBC control module has failed. Either way, if you are in the USA, this is now covered by a 25-year, unlimited miles, unlimited owners warranty - take it to the dealer. If they give you any grief:

 

·
Registered
Current: '07 SL550, '06 ML350 - Past: '99 ML320 (Sold), '98 SLK230 (Wrecked), 05 SL500 (Wrecked)
Joined
·
377 Posts
Discussion Starter #3
So you think this points to the SBC after all? If the SBC module has failed how come the brakes are currently working?
 

·
Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
Joined
·
18,991 Posts
If the brakes failed, there is something wrong with the SBC system. I'd get the dealer to look at it. If they can pull codes, they can see what is stored. If they can't communicate with it, either, then they will likely replace the control unit.
 

·
Registered
Current: '07 SL550, '06 ML350 - Past: '99 ML320 (Sold), '98 SLK230 (Wrecked), 05 SL500 (Wrecked)
Joined
·
377 Posts
Discussion Starter #5
Update:
Last week the same thing happened again, only this time, turning the engine of and waiting a few minutes then restarting it did not rest the system, so I made an appointment with the repair shop.

Put the car in the garage and waited for the appointment day. 3 days later when I had to take the car in, I started it and the error was gone and the brakes were working, but once they put the car on the rackand ran the diagnostics, sure enough it was the SBC, which Mercedes repaired for free. From what I can tell, there is a new SBC unit in place, and the paperwork says they also replaced the pump and some other parts.

Anyway, everything was free of charge. They did say that they recommend I have the motor and trany mounts replaced becuase they're "collapsed and causing excessive vibration". Which is funny because I can't feel any vibration at all, so I'm not sure where that came from, but at least I have brakes!
 

·
Registered
2003 sl55amg
Joined
·
69 Posts
Update:


They did say that they recommend I have the motor and trany mounts replaced becuase they're "collapsed and causing excessive vibration". Which is funny because I can't feel any vibration at all, so I'm not sure where that came from, but at least I have brakes!
You might want to check out your motor mounts! They are fluid filled, and if collapsed, the fluid is gone. The rubber must have separated from the metal for this to happen. You can test it by two ways.
1. Grab the motor and push it back and forth side to side. It should move smoothly.
2. Open the hood, start it and put it in gear with your foot on the brake, give it some gas. It should move very little. I'll bet yours rises up on one side 3-4 inches. You can see it between the hood and windshield or have someone help you. Once the motor mounts go, the trans mount soon separates too.
I'm sure many owners drive around with broken motor mounts blissfully (I did), but it will get worse. I changed my own on my slk 320, it was a hard job due to lack of clearance. I don't know about the r230 series but I'll also bet it's not easy.
 

·
Registered
Current: '07 SL550, '06 ML350 - Past: '99 ML320 (Sold), '98 SLK230 (Wrecked), 05 SL500 (Wrecked)
Joined
·
377 Posts
Discussion Starter #7
You might want to check out your motor mounts! They are fluid filled, and if collapsed, the fluid is gone. The rubber must have separated from the metal for this to happen. You can test it by two ways.
1. Grab the motor and push it back and forth side to side. It should move smoothly.
2. Open the hood, start it and put it in gear with your foot on the brake, give it some gas. It should move very little. I'll bet yours rises up on one side 3-4 inches. You can see it between the hood and windshield or have someone help you. Once the motor mounts go, the trans mount soon separates too.
I'm sure many owners drive around with broken motor mounts blissfully (I did), but it will get worse. I changed my own on my slk 320, it was a hard job due to lack of clearance. I don't know about the r230 series but I'll also bet it's not easy.
Thanks for the testing heads-up. I did just that this afternoon, and it does rise, but only about 1.5"-2", not 3" or 4". I guess I'll have to have an independent take a look and give me a second opinion.

I also checked and in my area, most shops want about $1500-1600 for the engine mounts and an additional $350-400 for the tranny mount. I think that's crazy.
 

·
Registered
2003 SL55; 2011 E350 BTC
Joined
·
441 Posts
1.5-2" movement is about right. You can look for videos on YouTube of bad motor mounts and see what is truly bad.
This is a 5 out of 10 job, and you can DIY all in for about $200 including the special 16mm motor mount wrench.

Hardest part is getting the car up in the air to work on it. Once in the air, and jack and block of wood under the engine will allow removal and replacement. This needs a new thread rather than this one...
 

·
Registered
2003 sl55amg
Joined
·
69 Posts
Thanks for the testing heads-up. I did just that this afternoon, and it does rise, but only about 1.5"-2", not 3" or 4". I guess I'll have to have an independent take a look and give me a second opinion.

I also checked and in my area, most shops want about $1500-1600 for the engine mounts and an additional $350-400 for the tranny mount. I think that's crazy.
Mine at 80K miles are still solid and don't rise at all. My slk320 were shot at 180K miles.
The parts are less than $500 for all three and can be changed without removing the engine (like on a V12), but need lots of parts removed to get them out, some say the exhaust manifolds, some just the AC compressor moved out of the way.
Yeah, it's crazy expensive, but what isn't these days!
 
1 - 9 of 9 Posts
Top