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Discussion Starter #1
Hello,

The SLK has the traction control light flashing constantly, mainly as I set off driving, but also wh3n the car is cold, It also goes in limp mode now and then (EMLon) and I get two fault codes P0720 and P0500.

My question is...the tyre sizes at the front are 205 55 16, however the two back ones are 225 55 16, Am right in saying that the back ones should be 225 50 16?

Also will these tyres be affecting the traction control?

Thanks

Niaz
 

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Premium Member 1999 SLK 5.4 M113
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I can say for sure that tire size will cause Cruise Control to stop working. or work for a second or 2.

I believe a 5% difference in aspect ratio should not matter too much. but it might.
 

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Discussion Starter #4
I can say for sure that tire size will cause Cruise Control to stop working. or work for a second or 2.

I believe a 5% difference in aspect ratio should not matter too much. but it might.



Thanks, ok great, I will look at the tyre issue. Regarding the speed sensor I don't think it is the issue, I think it maybe yo do with the transmission plug and conductor plate, as soon as you engage reverse it won't go in, you need to.select park and then reverse, also by doing yhis wjhen you then select drive again the car sticks to 1st gear only until you restart the car!
 

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Super Moderator UK SLK 55 AMG 2007
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25,406 Posts
No expert, but have seen threads where speed sensor stops cruise control operating.

There's some other threads in those two links I posted above that may fit your exact issue.

Remember the SLK mantra.

Quick,
Cheap,
Simple,
before going expensive.
 

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Discussion Starter #7
No expert, but have seen threads where speed sensor stops cruise control operating.

There's some other threads in those two links I posted above that may fit your exact issue.

Remember the SLK mantra.

Quick,
Cheap,
Simple,
before going expensive.
Thanks and totally agree, I can start with the sensors, however at the garage the mechanic hooked it to his better diagnostics and to told me it was showing the rear sensors were reading fault, however these were linked to transmission issues.

Once or twice a day I clear the fault codes and as long as I don't rev hard at the start or go into reverse, the car behaves and even at 70mph there is no limp mode the temp gauge stays at 95, even with this weather at 32 reg the fan and thermostat work etc so rest of car is spot on.

Yes, I have read a lot of these posts and done a few searches too.

I paid £1k for the car for some summer fun, which I am having. But I don't want to spend more than a few hundred pounds, as when I sell the car (sell for a loss) the new owner will able to look after it properly.
 

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Discussion Starter #9
Not sure if a light went on, or I have gone way into left field.

Does the issue hit at a certain speed, or at a certain rev range?

I can't for life of me see how it might relate to what I am thinking,
but never hurts to ask.

Also, expert time...

@Mn car guy
@efair
@stu32
@savcom

@Padgett
@Australian

Hi Pal,

Good question, I think the car starts off very slow even with the rev counter hitting 2 or 3k ( I dont think I see higher revs other than when it is stuck in 1st gear) and carries on slowly building speed, it's likes driving a manual car which has the clutch slipping, so no traffic light racing for me lol.
 

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I think the tyre size will matter when driving straight ahead, which the car knows due to steering angle sensor.
You are correct that the rear tyres should be 225/50 r16 . I would fix this first anyway as it could affect an insurance claim if wrong size tyres are fitted. You know what they are like if they can wriggle out of something.
 

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Super Moderator UK SLK 55 AMG 2007
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Experts...(which I am not) ignoring the potential speed sensor/tyres issue,
could the rest of this relate to the point where the Kompressor kicks in?
 

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Discussion Starter #12
I think the tyre size will matter when driving straight ahead, which the car knows due to steering angle sensor.
You are correct that the rear tyres should be 225/50 r16 . I would fix this first anyway as it could affect an insurance claim if wrong size tyres are fitted. You know what they are like if they can wriggle out of something.
Thanks, yes will do.

The car is definite sluggish on first 15mph as if it is starting in 3rd gear and then moves ok. On the motorway I had no problem with 70mph but the revs were about 2800, is this high?
 
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