SLK 2003 ASB/ESP and Limp Home Mode

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davidwmjones

New Member
Joined
May 4, 2006
Messages
5
Location
Birmingham, UK
Car
SLK 230
Hello

Great Forum people. Hello to you all. This is my first post so hopefully it is in the right place.

I have an SLK230 2003. The ABS and ESP lights came on a while ago, but I just ignored it as drove ok and I didn't have the cash (£60) for MB check.

Now, a week later it's gone into limp home mode.

I've tried changing the brake pedal switch (as shown/indicated here). If I reset the errors by moving the steering wheel left then right it comes back on about a second or so after I start the engine.

When I start the car, at first I can change down the gears (automatic) but after a drive a litle bit (20 meters or so), it sticks in whichever gear indicated on the dash (1/2/3/4) and is in the limp home mode (1st gear).

I noticed that in my boot (trunk) was very wet, full of moisture. Lots of water in the spare wheel and the foam around he PSE unit is very wet.

I've taken it to an independent garage wgo has the Star system and got lots of error codes.
ESP
C1102-004, C1103-002, C1103-004, C1103-016, C1200, C1120-004, C1202, C1025-002, C1025-004
ETC
P2400, P2401
ESM
P1861, P1860
(plus more) but generally indicating fault with both rear speed sensors and yaw rate sensor, and ABS faulty.

The garage think it's an electrical problem, probably a lose connection somewhere.

I've removed the centre console, inspected YAW, acceleration and looked at the rear speed sensors. Nothing obvious other that lots of water in the rear sensor plug where it connects to the main shell of the car on both sides. I've dried this as best I could.

I still have the problem. If I take it to dealer to do another diagnostic check, would they be able to give me any more information, is it worth it?

I'd like to repair it myself for the sense of achievement and also because I took it another Mecedes Specialist garage 6 months ago when it had exactly the same problem. Not a good experience with them, as initial quote of £50 went to £600 without asking. Then they replaced speed sensors and the ABS Pump Control Unit which I supplied second hand. Still that's another story.

Any ideas? Should I take it to a dealer, could it be the ABS Pump/ESP controller again?

Thanks in advance for any help
 
It needs to go on a Star again to have the fault codes read and tested. Anyone can read codes. Understanding the codes is the dificullt part.
 
Codes

Hi, sorry the readout I got from the garage has the desciptions of the codes on it. I just didn't post them as it's quite lengthy,

for example
ETC - Electronic transmission comyrol
P2400 The right rear wheel rpm signal sent from the traction system via the CAN bus is implausible.
and lots more, I can post all the codes and all the detials if you think it would help?
 
Because there are so many fault codes with your car it is almost impossible to determine the actual fault. They need to be erased and when the warning light re-appears the "fresh" codes can be re-checked. The list of codes you have is quite unusual.
 
Codes cleared

I returned the car to the specialist garage and got all the codes cleared and the lights on the dash went away. I then drove it out of the garage and lights came back on and back into limp mode.
Put it back on the machine (STAR system) and long list of the same codes appeared. CAM Bus errors, rear sensor errors......
So I'm going to try replacing both the speed sensors at the back and see how that goes. The sensors were actually replaced 6 months ago before by another independent garage but the water may have damaged them.
I've tried cleaning the connectors (electrical contact spray) but no joy.
I think I should try and clear the drains too, as I think they've become blocked and may be the cause of my problems.
 
Update.

So I've replaced the rear speed sensors, drove the car and it changed down gear and the warning lights went off as well (after driving a bit). So it looks like it's all fixed, even drives smoother than before.
The old speed sensors look like the new ones but seem to have had the Mercedes Logo filed off them. Suspicious, may have been second hand.
From what I have gleaned, my car has a CAM Bus system. This is one 'Ring' shared by all the sensors and loops vabck back to the control box. As a result if any one of the sensors on the ring is faulty, it can give 'strange' readings about everything (any other component on the ring i.e. everything). So if there's lots of errors just go for replacing the standard/cheapest components. Last time the garage changed the ESP control system (didn't fix it), and then the speed sensors. I don't think it was necessary (and expensive) to replace the ESP module. But that's hindsight I guess.
It's great to work on my car and even fix it! Learnt loads and you will always do the best job when it's your own vehicle. :)
 

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