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Registered 1998 SLK230
Joined
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62 Posts
Discussion Starter #81
This is so exiting. Will it be the fan controller...
Can’t wait for the next episode.
I just love this forum (y) :)
Happy to oblige.... It's NOT the fan controller. Put the new one in, turned on the A/C - no fan movement... I took it for a long drive - radiator light came on and off repeatedly during the drive. It maintained about 80-110c for most of the ride, even at idling. After driving for about 40 minutes, it finally started creeping higher in temp. When I reached home, it was very close to the top of the gauge. Got it home to the driveway, still running, and within seconds, it hit the 'red zone' (but I shut it off before I saw any steam/boiling overflow).


Anything?
 

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Premium Member 2001 SLK200K/2001 SLK320
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2,091 Posts
Happy to oblige.... It's NOT the fan controller. Put the new one in, turned on the A/C - no fan movement... I took it for a long drive - radiator light came on and off repeatedly during the drive. It maintained about 80-110c for most of the ride, even at idling. After driving for about 40 minutes, it finally started creeping higher in temp. When I reached home, it was very close to the top of the gauge. Got it home to the driveway, still running, and within seconds, it hit the 'red zone' (but I shut it off before I saw any steam/boiling overflow).


Anything?
That's bad news but good info (y)

Which now leaves ..

Circuit between ECU and Fan Controller (PWM Signal wire) ............

Main Power / Earth to Controller Circuit, has anyone actually put a Headlamp Bulb across these 2 connections, to load that circuit, that Bulb should light up real bright !!

ECU Fault
:confused:
 

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Premium Member 2001 SLK200K/2001 SLK320
Joined
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2,091 Posts
The three remaining possibles that Dave has listed need to be explored first of course but a solution, not a fix as such would be to wire in an independant electric fan controller such as the Flex-a-Lite 31165 or similar ..

Just putting that out there :devilish:
 

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Premium Member 2002 R170 SLK V8 5.0
Joined
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3,175 Posts
PWM stands for Pulse Width Modulated and it is a signal from the Engine ECU which tells the Fan Controller what speed to run the Fan at, that is a GREY Wire.

Earth is the thick Brown Wire that goes to Fan Controller, and the 50 Amp Pre Fuse is connected to the Fan Controller by the thick Black / Green or Black Wire.

Then there is the 12V +ve Ign On feed from Pink / Red which should be checked with a load for a decent 12V+ ...............................



HTH :)
 

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Registered 1998 SLK230
Joined
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62 Posts
Discussion Starter #87
PWM stands for Pulse Width Modulated and it is a signal from the Engine ECU which tells the Fan Controller what speed to run the Fan at, that is a GREY Wire.

Earth is the thick Brown Wire that goes to Fan Controller, and the 50 Amp Pre Fuse is connected to the Fan Controller by the thick Black / Green or Black Wire.

Then there is the 12V +ve Ign On feed from Pink / Red which should be checked with a load for a decent 12V+ ...............................



HTH :)

What would you need to test these wires?
 

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Registered 1998 SLK230
Joined
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62 Posts
Discussion Starter #89
You will need a multimeter. They are readily available at hardware stores, online, etc. Less than $50 for a decent one. Chances are someone you know has one, and can help you out. If not, there are plenty of videos on YouTube on how to use one.

Good luck
Oh, OK thanks! I'm the daughter of an electrician, so I do have one of those ;)
 

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Premium Member 2002 R170 SLK V8 5.0
Joined
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3,175 Posts
What would you need to test these wires?
You will need a multimeter.
I'm sorry to have to say this, and I appreciate that everyone is entitled to post their own info, but I wrote ....................

Main Power / Earth to Controller Circuit, has anyone actually put a Headlamp Bulb across these 2 connections, to load that circuit, that Bulb should light up real bright !!
You cannot test Power and Earths with a Multimeter, unless it has a suitable load across that Circuit, which is why I said which Wires to use a Bulb (load) test on ;)

You also cannot use a Bulb to test ECU outputs, things like PWM in this case, or other Computer (ECU / Module) outputs like Injectors etc, you then need more specialised equipment like Noids or Oscilloscope.

Power Circuits means a FUSED CIRCUIT and it's Ground, Earth, or Negative and to test these the cheapest way is to use a simple test lamp, like a 55W Headlamp bulb for the Pre Fuse and Earth Circuits, (50 Amp One) and for the smaller Ign On +ve should use something like a 21W Indicator Bulb.

Multimeters detect feedback on DC Circuits and can often read 12.5V(olts) on a dead circuit, because there is no A(mps) drawn.

Which is why I posted the Wiring Diagram above so you can see how it works.

The only reason I have posted this this morning is because I have seen it on here and on other forums lots, and whilst this post may sound "crabbit" it is for clarification and explanation purposes ..................

If those knowledgeable members read that OP has 12.5 Volts then we are just as likely to all end up going off on a Tangent looking for something else..................

HTH ;)
 

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Premium Member 2005 SLK200K 'Little Growler'
Joined
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962 Posts
I'm sorry to have to say this, and I appreciate that everyone is entitled to post their own info, but I wrote ....................



You cannot test Power and Earths with a Multimeter, unless it has a suitable load across that Circuit, which is why I said which Wires to use a Bulb (load) test on ;)

You also cannot use a Bulb to test ECU outputs, things like PWM in this case, or other Computer (ECU / Module) outputs like Injectors etc, you then need more specialised equipment like Noids or Oscilloscope.

Power Circuits means a FUSED CIRCUIT and it's Ground, Earth, or Negative and to test these the cheapest way is to use a simple test lamp, like a 55W Headlamp bulb for the Pre Fuse and Earth Circuits, (50 Amp One) and for the smaller Ign On +ve should use something like a 21W Indicator Bulb.

Multimeters detect feedback on DC Circuits and can often read 12.5V(olts) on a dead circuit, because there is no A(mps) drawn.

Which is why I posted the Wiring Diagram above so you can see how it works.

The only reason I have posted this this morning is because I have seen it on here and on other forums lots, and whilst this post may sound "crabbit" it is for clarification and explanation purposes ..................

If those knowledgeable members read that OP has 12.5 Volts then we are just as likely to all end up going off on a Tangent looking for something else..................

HTH ;)
Double 👍🏻 to that Dave.
 

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Registered 1998 SLK230
Joined
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59 Posts
I'm sorry to have to say this, and I appreciate that everyone is entitled to post their own info, but I wrote ....................



You cannot test Power and Earths with a Multimeter, unless it has a suitable load across that Circuit, which is why I said which Wires to use a Bulb (load) test on ;)

You also cannot use a Bulb to test ECU outputs, things like PWM in this case, or other Computer (ECU / Module) outputs like Injectors etc, you then need more specialised equipment like Noids or Oscilloscope.

Power Circuits means a FUSED CIRCUIT and it's Ground, Earth, or Negative and to test these the cheapest way is to use a simple test lamp, like a 55W Headlamp bulb for the Pre Fuse and Earth Circuits, (50 Amp One) and for the smaller Ign On +ve should use something like a 21W Indicator Bulb.

Multimeters detect feedback on DC Circuits and can often read 12.5V(olts) on a dead circuit, because there is no A(mps) drawn.

Which is why I posted the Wiring Diagram above so you can see how it works.

The only reason I have posted this this morning is because I have seen it on here and on other forums lots, and whilst this post may sound "crabbit" it is for clarification and explanation purposes ..................

If those knowledgeable members read that OP has 12.5 Volts then we are just as likely to all end up going off on a Tangent looking for something else..................

HTH ;)
@ Dave2302 Quite right, Dave. I was thinking in general terms of a multimeter being used for testing purposes. I do appreciate the correction, as well as the information you provided.

Ok, off to put the humble pie in the oven now. :)
 

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Registered 1998 SLK230
Joined
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62 Posts
Discussion Starter #94
I'm sorry to have to say this, and I appreciate that everyone is entitled to post their own info, but I wrote ....................



You cannot test Power and Earths with a Multimeter, unless it has a suitable load across that Circuit, which is why I said which Wires to use a Bulb (load) test on ;)

You also cannot use a Bulb to test ECU outputs, things like PWM in this case, or other Computer (ECU / Module) outputs like Injectors etc, you then need more specialised equipment like Noids or Oscilloscope.

Power Circuits means a FUSED CIRCUIT and it's Ground, Earth, or Negative and to test these the cheapest way is to use a simple test lamp, like a 55W Headlamp bulb for the Pre Fuse and Earth Circuits, (50 Amp One) and for the smaller Ign On +ve should use something like a 21W Indicator Bulb.

Multimeters detect feedback on DC Circuits and can often read 12.5V(olts) on a dead circuit, because there is no A(mps) drawn.

Which is why I posted the Wiring Diagram above so you can see how it works.

The only reason I have posted this this morning is because I have seen it on here and on other forums lots, and whilst this post may sound "crabbit" it is for clarification and explanation purposes ..................

If those knowledgeable members read that OP has 12.5 Volts then we are just as likely to all end up going off on a Tangent looking for something else..................

HTH ;)
Thanks for the detailed response, Dave2302... It's waaaay above my pay grade, and may as well be written in Chinese Characters in terms of what I'm understanding, but I will pass it along and see if my friend is able to use the info in a meaningful way. In the meantime, I ordered a Flex-A-Lite just so I can drive, and while I'm trying to figure it out.

My friend purchased a set of light probe things today. Is that what you are referring to when you say a test lamp?

Thanks again!
 

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Premium Member 2002 R170 SLK V8 5.0
Joined
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3,175 Posts
My friend purchased a set of light probe things today. Is that what you are referring to when you say a test lamp?
Only IF the "light probe thing" has regular bulb, or some way of putting a decent load on the Circuit.

This Fan Control has 6 Wires going to it, I have given you the Wiring diagram.

This should take under 5 mins to eliminate 5 Wires ....................

Un Plug Fan Controller .............

Jump from battery + to pin 4 and battery - to pin 1, if fan runs fast you now eliminated the Fan and it's Wires.

Test Bulb of 21W to 55W between Pins 2 and 3 if bulb lights bright you now eliminated the Controls main power and earth

Test Bulb of 5W to 21W between Earth and pin 6 if bulb lights bright you know eliminated the Ignition +

Which then leaves you with PWM Wire from pin 5 at controller to pin 4 ECU un plug from bot Modules and check that it has continuity !!

If that wire is good then either you have some kind of ECT Sensor Issue, or the ECU is u/s not putting out the PWM Signal.

At that point you now need SDS and possibly an Oscilloscope.

If you cannot work that simple "Bulbs and Battery" procedure from the easy to read Wiring Diagram then I'm sorry, but I'm gonna have to suggest that you take this to someone who can ;)

HTH,
 

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Premium Member 2002 R170 SLK V8 5.0
Joined
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3,175 Posts
My friend purchased a set of light probe things today. Is that what you are referring to when you say a test lamp?
This issue does not need $$$$ constantly chucking money at it ;)

You will soon be at the point you would have been cheaper to just take it to the MB Main Dealers :eek:

This is what I use for verifying Power and Earth Circuit integrity, which cost almost nothing and was made in 5 minutes from an old 21W Bulb and holder and a length of wire :-



HTH,
 

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Premium Member 2005 SLK200K 'Little Growler'
Joined
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962 Posts
This issue does not need $$$$ constantly chucking money at it ;)

You will soon be at the point you would have been cheaper to just take it to the MB Main Dealers :eek:

This is what I use for verifying Power and Earth Circuit integrity, which cost almost nothing and was made in 5 minutes from an old 21W Bulb and holder and a length of wire :-



HTH,
Very nice description @Dave2302
 

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Registered 1998 SLK230
Joined
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62 Posts
Discussion Starter #98
Dave thanks SO much for the detailed information. Just so I’m clear, are these the types of lamps that would work for testing?
581775


I’m not sure what I’ll be able to do here with this info. I’m going to try, but I honestly couldnt even change a tire before getting this SLK. I’m avoiding taking it to the MB dealership not only because of cost, but also because I’m trying to learn to not be afraid of what’s under a hood anymore.

So far, with the help of the good people in this forum, I’ve learned to replace a fan, fan controller, map sensor, MAF, and temp sensor.

I can admit the electrical stuff is going to be waaay over my head. I’m going to give it a try though since you were so kind to give so many details to help me out.
 

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Premium Member 2002 R170 SLK V8 5.0
Joined
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3,175 Posts
I don't know, cannot see if those have Bulbs or LED's anywhere, also they may have electronics, a very simple bulb Tester is what is required here, but most Auto Factors etc don't sell them any more they are all LED things these days, which don't load the circuit enough.
 
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Registered 1998 SLK230
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62 Posts
Discussion Starter #100
I don't know, cannot see if those have Bulbs or LED's anywhere, also they may have electronics, a very simple bulb Tester is what is required here, but most Auto Factors etc don't sell them any more they are all LED things these days, which don't load the circuit enough.
Thanks. Here is what is inside.
 

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