My first Mercedes maybe my last!

[Razor4173]

Hi this is my first forum post. Looking for some help and guidance on how to diagnose and fix a fault on my car. I own a C220 W204 automatic estatw car 2008 plate with 107701 miles on clock.

I have had a reoccurring fault with the car. As soon as i get to 65mph or 70mph a yellow triagle warning triagle illuminates and I lose power. Two messages are then display: 1 Cruise Control and Speed control inoperable. 2. Traction or stability control inoperable take to workshop.

I read many MB forums and many directed my attention to the brake light switch. I bought one and replaced accordingly. It did not fix the issue at all.

I have taken my car to 3 different garages, the last being a mercedes specialist. All have put on the computer and none have fixed the issue. I have had work done on the car and in a twelve month period i have spent over £2000 on electronuc repairs. I thought Mercedes were reliable but turns oout the worse car i have ever owned.

The car is causing me stress and anxiety as dangerous to drive when losing power on straight roads or worse on hills.

I feel let down by the 3 garages as had a belief that when connectted to a computer it told the mechanic what was causing the fault or which sensor needs replacing. This is not the case.

If anyone had a similiar issue and was able to fix then please advise. Other the car is being take to car auction.

Many thanks

 

[the director]

Sounds to me like a speed sensor failure on one of the wheels......car can’t work out how quick wheels are turning relative to the others so, shuts down the abs/traction control/cruise control just to be on the safe side.

Probably less than £200to fix (including an hour for labour).

 

[LostKiwi]

What size tyres do you have all round?

 

[Naraic]

As above...do you have the correct size tyres all round?

 

[EmilysDad]

that when connectted to a computer it told the mechanic what was causing the fault or which sensor needs replacing. ....

Welcome.
Diagnostic kit is only as good as the bloke holding it.

 

[Craiglxviii]

Sounds like a rusted up reluctor ring to me. Wheel speed sensor in other words. That would throw cruise control and traction control off.

 

[EmilysDad]

Sounds like a rusted up reluctor ring to me. Wheel speed sensor in other words. That would throw cruise control and traction control off.

Surely someone in 3 garages, including a Merc specialist, would have picked up on something so obvious ....

 

[LostKiwi]

Surely someone in 3 garages, including a Merc specialist, would have picked up on something so obvious ....

Reluctors normally give issues at low speed in my experience but its certainly worth looking at.

 

[EmilysDad]

Reluctors normally give issues at low speed in my experience but its certainly worth looking at.

Certainly the case on my Roadster ..... 'chirp' of the ABS as I came to a complete stop.

 

[LostKiwi]

Certainly the case on my Roadster ..... 'chirp' of the ABS as I came to a complete stop.

Same on the 129....

 

[Steve@Avantgarde]

204’s have 2 issues with ABS. The speed sensors and the ABS pump.

If you have had sensors replaced and they haven’t been mercedes genuine ones then I would replace them with genuine parts. The reason is the sensors have been modified and must be replaced as pairs across an axle.

The ABS pumps suffer with internal failures. But can be repaired.

There are 2 TIPs documents on this and it also affects the early R172’s.

As someone has also pointed out. Check the speed ratings and size of your tyres to make sure they match across an axle.

Lessons to be learned - never throw parts at a car based on a forum guess with no evidence that it will actually fix your fault. That can be potentially dangerous. Forums are a wealth of knowledge but no one can be sure over the net.

Research the garages you use, even some specialists have limited knowledge of the products.

 

[LostKiwi]

Check the speed ratings and size of your tyres to make sure they match across an axle.

And front to rear sizes aren't incorrect.

 

[umblecumbuz]

Would agree with all the above, except that no symptoms occur until c.70mph is reached, and presumably the car drives nrmally on a restart until such a speed is reached again.

Puzzling ... could it be a bad connection on one of the wheel speed sensor leads that only shows up at speed? Vibrational? My experience is limited, but when I've had a speed sensor fault in the past and taken live readings while driving, the discrepancy shows up at any speed.

Can't see a yaw rate sensor being the cause, or the steering angle sensor, as at such a speed you are presumably not hammering the car round sharp bends, but driving in a straight line (yaw sensor on yours is under the passenger front seat carpet. Seat needs to be removed, plus door sill trim to get to it. Engine off, key out. Easy swap, and cheap.)

I would break and remake all the possible connections as the next step - including the multiplug on the Abs unit. Dry joints, if it is such, don't like vibration.

Does the autobox play up when this happens, or does it continue to change normally? I would expect it to short shift. You've come to the right forum - there are knowledgeable guys on here who will offer more help as they spot your post.

 

[Steve@Avantgarde]

And front to rear sizes aren't incorrect.

Bit of a bump steer that, most Merc have offset wheel sizes which are different front to rear. EG 225 45 18 front and 245 40 18 rear. In this instance the ABS knows the difference. Speed ratings of tyres will have a massive effect.

 

[LostKiwi]

Bit of a bump steer that, most Merc have offset wheel sizes which are different front to rear. EG 225 45 18 front and 245 40 18 rear. In this instance the ABS knows the difference. Speed ratings of tyres will have a massive effect.

Yes but if someone has incorrectly fitted 45 profiles both ends to a staggered setup....

 

[Steve@Avantgarde]

Would agree with all the above, except that no symptoms occur until c.70mph is reached, and presumably the car drives nrmally on a restart until such a speed is reached again.

Puzzling ... could it be a bad connection on one of the wheel speed sensor leads that only shows up at speed? Vibrational? My experience is limited, but when I've had a speed sensor fault in the past and taken live readings while driving, the discrepancy shows up at any speed.

Can't see a yaw rate sensor being the cause, or the steering angle sensor, as at such a speed you are presumably not hammering the car round sharp bends, but driving in a straight line (yaw sensor on yours is under the passenger front seat carpet. Seat needs to be removed, plus door sill trim to get to it. Engine off, key out. Easy swap, and cheap.)

I would break and remake all the possible connections as the next step - including the multiplug on the Abs unit. Dry joints, if it is such, don't like vibration.

Does the autobox play up when this happens, or does it continue to change normally? I would expect it to short shift. You've come to the right forum - there are knowledgeable guys on here who will offer more help as they spot your post.

Personally I wouldn’t do or advise anything until we know what fault codes are stored. Especially with ABS.

But faults on the ABS can be speed related especially if the tyres are wrong or the sensors are the incorrect issue for the car.

 

[Steve@Avantgarde]

Yes but if someone has incorrectly fitted 45 profiles both ends to a staggered setup....

In past experience I wouldn’t see that as too much of an issue. I have upped wheel sizes without a staggered set up before with no issues.

I would say that a 40 on one side and a 45 on another side would though.

I could be wrong though.

 

[Razor4173]

Sounds to me like a speed sensor failure on one of the wheels......car can’t work out how quick wheels are turning relative to the others so, shuts down the abs/traction control/cruise control just to be on the safe side.

Probably less than £200to fix (including an hour for labour).

Thanks for your reply i will speak to my local garage and discuss as an option. Still surprised that when you connect a computer it is of no help.

 

[Steve@Avantgarde]

Thanks for your reply i will speak to my local garage and discuss as an option. Still surprised that when you connect a computer it is of no help.

Unless they are using STAR diagnosis it’s likely their computer is of no help.

 

[LostKiwi]

Thanks for your reply i will speak to my local garage and discuss as an option. Still surprised that when you connect a computer it is of no help.

Unless the diagnostic is Mercedes specific it may show nothing at all. Even then unless its STAR it may only give a partial picture.