Mercedes SLK World banner

1 - 7 of 7 Posts

·
Registered 2004 SLK320
Joined
·
15 Posts
Discussion Starter #1
As others have said, our pages have plenty of discussion and ideas on this one, but no concrete solution., Everything is fine until the engine reaches operating temp of 80 C or so, then all hell lets loose = the fan kicks in at roaring high speed and stays there until you switch off. There are no warning lights, and the all indicators are normal, including engine temp..AC works fine.
My normally excellent garage has tried everything including switching the ECU,and control module,..and all the voltages and continuity checks done.
All the diagnostic testing keeps coming up with error codes that put the blame on the control module instrument cluster (see attached) ..maybe someone can interpret that,
One question asked earlier to which I see no answer is where the variable voltage to change the fan speed is generated? If all else fails we're thinking of putting in a relay or shunt to drop the 'constant' and/or a manual switch in the fan power line. Drive and temperature watch!
With that data, has anyone got any suggestions? Experience or divine inspiration welcome !
Merc work.jpg
 

·
Registered 2004 SLK320
Joined
·
15 Posts
Discussion Starter #3
I haven't , but have ordered one to try....but would not a faulty one result in incorrect analogue readings on on the dashboard ? ...having driven the car short (2-3 mile) distances with the fan computer disconnected while carefully monitoring the temperature gauge, it (the gauge) shows exactly the readings I would expect.
 

·
Premium Member 2002 R170 SLK V8 5.0
Joined
·
3,485 Posts
One question asked earlier to which I see no answer is where the variable voltage to change the fan speed is generated?
PWM Signal is sent from the ME (Engine ECU) to the Fan Controller on left front inner wing. It is the PWM Signal that tells the Controller what percentage speed to run the Fan at.

Reading that you mechanic has changed the Engine ECU, I would suspect the Fan Controller ............ (How he got it to start after swapping the ME surprises me as it's part of the Theft Relevant Parts = Immobiliser), but perhaps he is one of us few who are clever enough to do programming work and he cloned it ;)

If the Car has had an ME Change in the past, or even some kind of bad re map, it just may be the Version Coding for Cooling Fan is wrong, I'd check that too, it needs SDS which is the proper MB Diagnostic Machine.

What happened when the mechanic did the varying percentage Speed Tests with his SDS ?

HTH ;)
 
  • Like
Reactions: M4rCu5

·
Registered 2004 SLK320
Joined
·
15 Posts
Discussion Starter #5
Really appreciate your help and suggestions on this one Dave. I now understand they haven't yet switched the ECU......that is to be the last resort . They have now got a replacement instrument cluster, being convinced, from the SDS, that the problem lies there. To be tried later nest week...is this a starter?

PS.. would love to see a pic of your V8 squeezed into the R170..!:oops:
 

·
Premium Member 2005 SLK55 AMG; 2005 SLK350
Joined
·
5,220 Posts
Definitely resolve that code before you do anything - when the ECU is missing input, it often assumes"safe mode", taking the least risky approach, which might include "max cooling".
 

·
Premium Member 2002 R170 SLK V8 5.0
Joined
·
3,485 Posts
I'm gonna go out on a limb here, and say I don't think it's anything to do with Cluster, but of course I will stand corrected as ever ;) I suppose stranger things have happened with any MB 🤣

The way I understand it is this, Temp Sensor tells ME the Temp, ME transmits that to cluster via CAN, also when at set temp ME Generates the PWM signal to start fan at 20%, and if temp keeps going up it keeps increasing the speed via PWM ;)
That is certainly how it works on many many MB's however R170 does do a few things kinda in between Old Skool Merc and the 2000 to 2010 MB's, so never say never ;)

I do know for a fact the PWM Signal from the R170 to it's external controller is exactly the same as all the others with the later fans that use built in Controller, because that's what I have used on the V8, a later slimmer C Class 600 Watt Temic with controller built in ;)

V8 Pix ?? Pix ?, Pix ?, how many ya want ??? :D :D :D

Car has a mega long full build thread starting from just before I bought it as a 320 V6, in "Performance MODS for the R170" section of SLK World ............

Here :-


And here's a few of the most recent ones ( click to enlarge) ....





























:) :) :)
 
  • Like
Reactions: M4rCu5
1 - 7 of 7 Posts
Top