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*Registered
1999 SLK200K
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39 Posts
Discussion Starter · #1 ·
Hello,
I am having this problem with my SLK R 170, 1999 series, and for the past 8 months the car stops while running, and then I must wait , 20 min till it starts again, or the most, 1 hour.
Today, I went to the authorised dealer in Greece, the best one we have, and he wrote that I need to change the K 47 multirelay.
Is that it? Does he mean the K40? Why did he say K47?
I saw here in the forum that the K40, is responsible for many functions, among then the engine control, which I think this is the problem, when overheated. The problems that you are reffering here, and which I have, point at the K40 relay.

I just wanted to know if he means the same relay, refferring to as K47 multirelay, but he means the K40.
I searched everywhere, there is no such thing as K47.
If I ask him he will not answer, so please if you can help me, in this. Is it the same?
Is there a specific code numper for all of them?
Where can I look this up?

thank you very much!
 

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*Administrator (Premium Member)
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43,403 Posts
First off (and I am no expert) your right about no K47.
Azure Purple Rectangle Font Violet

Source:

Does this only happen in hot weather?

Not on a 170 but both cps for camshaft and crankshaft had this effect on my 171.
Genuine parts are cheap.

Have a look through these threads for similar.
 

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*Premium Member
1997 SLK230K
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973 Posts
I'm sure you'll get more advice in due course. However IF you need to change the K40, it's part number is clearly on the unit. Have a look at YouTube r170 K40 , called also the RCM (relay control module). Some of the videos refer to the Chrysler Crossfire. Or if you post your VIN someone will sort it out for you. However wait for advice from our experts. It's a bit concerning your comments on the main dealer. Are there any independent Mercedes workshops in your area?
 

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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
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9,033 Posts
He's got it saved on "speed-type" 🤣
I wish I did have, I'm simply not that efficient, and also depends on wot pooter I'm using, in the House is Windows and Workshop is Ubuntu, they don't share well ;)
 

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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
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9,033 Posts
If I translate that using Binary to Hex to Decimal equations and then divide it by Italian Typo to Germanglish it translates to K40 :)

Is there a specific code numper for all of them?
Where can I look this up?
Everything from a connector to a solenoid to a module etc etc has an ID number, the location of these parts on the car can be found using "Starfinder" Program.

K40 is found in the "Equipment Box" next to the Vehicle Battery in between the ME ECU and the CCM

HTH ;)
 

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*Premium Member
1997 SLK230K
Joined
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973 Posts
@Dave2302 , that doesn't really address her problem, which is partly motor related and partly I suspect due to the, well I'll politely call it, patriarchal nature of Greek society. Mind you I havn't been there for 30 years so maybe something has changed. I suspect she is going to have to throw parts at the issue? Based on similar issues on a BMW and a Saab, I'd probably go for the camshaft position sensor first as suggested by @Avel Du . It's not too expensive and easy to do.
 

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*Administrator (Premium Member)
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43,403 Posts
That was my thinking @Rofa Cheap to sort, but we do know K40 failure is common.
And as said, needs to be a proper K40, not cheap internet copy as they can fail faster than oem, or not even work from day one.

K40 location, from the link I posted in number 3 (I love that link!)
Circuit component Automotive lighting Font Auto part Automotive exterior


One thing to bear in mind when looking at diagrams is there being right handed and left handed versions of the car. I 'think' this is for US/EU left version, but if it looks different, look on opposite side of the car.
 

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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
Joined
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9,033 Posts
@Dave2302 , that doesn't really address her problem,
I thought she wanted to know where K40 was located, hence Starfinder suggestion.
I specified Box next to Battery to avoid left and right confusion ;)

The mechanic guy obviously meant K40, but got it wrong, yes the Hex Binary was in jest, it is "currently relevant for me" humour that I thought those who know what I'm doing atm would appreciate, (hacking a VGS 2 so a 7G Tronic Transmission will work properly in my V8 R170) ;)

Without proper diagnosis it would be a best / cheapish guess to chuck a Crank Position Sensor on it first, but you know me, I don't do parts darts (too often) ;)

HTH ;)
 

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*Premium Member
2001 SLK320
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2,466 Posts
Without proper diagnosis it would be a best / cheapish guess to chuck a Crank Position Sensor on it first
HTH ;)
I would agree with this .

However........... probably the most common fault with the K40 is that it prevents the engine from cranking. This is usually accompanied by the engine cooling fan running full speed. If your fan is doing that while failing to crank (with the ignition on) then I would change the K40. If not, then I would change the Crank Position Sensor first.
 

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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
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9,033 Posts
/\ /\ /\ I agree, we really need more info, i.e. Is it Cranking or not ;)

"Doesn't start" is simply not enough ;)
 

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*Registered
2003 SLK320
Joined
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35 Posts
Hello,
I am having this problem with my SLK R 170, 1999 series, and for the past 8 months the car stops while running, and then I must wait , 20 min till it starts again, or the most, 1 hour.
Today, I went to the authorised dealer in Greece, the best one we have, and he wrote that I need to change the K 47 multirelay.
Is that it? Does he mean the K40? Why did he say K47?
I saw here in the forum that the K40, is responsible for many functions, among then the engine control, which I think this is the problem, when overheated. The problems that you are reffering here, and which I have, point at the K40 relay.

I just wanted to know if he means the same relay, refferring to as K47 multirelay, but he means the K40.
I searched everywhere, there is no such thing as K47.
If I ask him he will not answer, so please if you can help me, in this. Is it the same?
Is there a specific code numper for all of them?
Where can I look this up?

thank you very much!
Similar problem with my 320. replaced the crankshaft position sensor. No further problem.. Tip. raise the bonnet fully to the near vertical position. Make access much easier.
 

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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
Joined
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9,033 Posts
I remember the first fix for the K40 is to resolder all the pins. They are susceptible to cold solder joints. It fixed mine.
It also fixed mine.
Sometimes it does fix them yes.

However a lot of other things also go wrong with them, and will do given time, some of those issues are with PCB and un fixable.

They are circa £170 from MB Dealer Parts dept.

5 mins to change it.

They last 20 yrs +

If it takes you an afternoon to fix it, it still has risk of sudden and imminent failure one dark wet night in the eerie forest, for me I'd rather just pony up the dosh, dry my eyes and spend that afternoon with my family / friends / driving and enjoying my Car etc etc ............... Or earning way more than the measly £170 ............ And no I'm not "made of money" at all ;)

Sorry fellas, no brainer for me ..................

Trash Can and fit a new one ;)
 

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*Registered
1999 SLK200K
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39 Posts
Discussion Starter · #20 ·
@Maria V
See the above comments and let us know.

Pointless folk responding further until we have more information & we know that you are still reading your own thread.
I have looked at all the answers and it seems they helped a lot, thank you very much! There is no need to be aggressive.
 
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