2007 Volvo S40 2.4 Non Turbo - Cooling Fan Not Operating -Code 6100

UPDATE: ISSUE IS FIXED

HI All,

I have been diagnosing a cooling fan issue on the Volvo. When I first received the car, it was hacked up. Someone installed a toggle switch to the fan and then later installed a cooling fan relay setup and epoxied a temperature probe to the radiator. After repairing the factory harness and removing all the clutter, I noticed the fan was always on even with the key out of the ignition, so I told the shop to get another one. The new "used" one stays f off now but the computer still throws a code 6100 for the control signal.

I replaced the 50amp fuse as it was blown. There is power and ground on the main feeds and I do get 12v from the fan control module on the control wire to the ECM. I can pull the 12v down with an incandescent test light easily. I am going to check at the computer for the control signal and check for breaks in the wire.

My main question is, even when the computer throws a fault code for the cooling fan, am I supposed to see a control signal from the ECM? On an oscilloscope there is only a flat line 12-14v at the fan module. I'll test at the ECM tomorrow. I ran out of time.

My main question is, even when the computer throws a fault code for the cooling fan, am I supposed to see a control signal from the ECM?

That's a good question. I've seen fan controller systems like this that use a 0% pulse width when the fan is not commanded, and others that use an 'idle' pulse width of less than 10% when the ECM is on but not commanding any fan speed.


I dug around in SI, and it's pretty vague:



As for what the signal itself is supposed to be, this is all you get:



If I had to hazard a guess, I'd suspect that whoever did the hacked up fan job got into the signal wire somewhere you haven't seen yet. :silly: I think your plan of getting to the ECM is your best testing option.

Thanks for the reply.

I figured out what was going on and made a video of how to test the circuit and how it works.

At some point, someone replaced the ECM and the engine wire harness but they installed the wrong harness. The control terminal and wire was missing from the ECM "B" connector. The connector was never wired for it originally. So I had access to another harness from a similar year Volvo and removed the terminal and wire for the fan control and starter relay circuit since that also had issues. I then made a home in the original ECM connector and put in the terminal for the fan control and replaced the starter relay terminal.

I'll work on posting pictures and video soon.

When the ECM want the fan off, it does not ground the 12v on the control wire at all, the control wire stays high.

When the ECM does control it, it pulls the 12v down. I did not measure the frequency or pulse width or duty cycle but in the video you can see what happens. Also in the video, i command the fan on to 100%.

I did find in service info that when the fault occurs, the fail-safe is FAN OFF.

Here is the video


Pictures next post...

The slot I needed to insert the new terminal in has a chunk of plastic missing from the female end. Looks like someone was messing with it at one point.


New terminals and wires installed.





Using the TOPDON Phoenix Smart, the software shows the PWM % as "RPM". I'll need to send feedback on that. However the fan is controlled and the engine temperature is regulated.


Testing circuit with test light. (Love the handheld oscilloscope / Multimeter. Not as good as my SnapOn Verus but my go to tool everytime.)

Great to hear you got it figured out.

A bit off topic, but I'd love to hear more about your experience with the Owon scope/meter. :woohoo: I was recently eyeing a Hantek and an Owon on Amazon:

www.amazon.com/Hantek2D42-Oscilloscope-G...ction/dp/B07PY6GHB5/

www.amazon.com/Oscilloscope-Universal-In...imeter/dp/B094FR78JB

They both look solid. But I couldn't tell if they would be all that much better in daily use compared to the Vantage or the Triton D8 I already have. :huh:

The OWON handheld oscilloscope is great I think. What I like about it, is the portability, ease of use, both multimeter and oscilloscope. Has clean waveforms and does what I need it to do. I didn't get the one with the waveform generator. Kind of bitting myself in the butt for that. I think it would have been useful on this Volvo case. Wondering if I could have injected a 100hz pulsed square wave into the fan control module to turn the fan on and test the component.

I mainly use it to see if there is a signal pattern at all, whether its a PWM, AC signal or variable voltage from a potentiometer. I do also use it for current measurements with both my current clamps in both multimeter and oscilloscope modes. I don't use it to really get detailed analysis, even though you can zoom right in on a signal very clearly. If you can pause it at the right point or have it take a single snap shot correctly, then extreme details might be evident. Its hard to get it to trigger in one spot on the screen. It only has a horizontal trigger and no vertical trigger so it will trigger perfectly fine, but at random spots on the screen. Example is the SnapOn verus d10, I can pin point at what location horizontally where I want it to start drawing after the trigger. I can't do that with the OWON. Maybe you can with the hantek.

I did test the accuracy of the voltage and current readings compared to my benchtop rigol components and both voltage and current readings matched exactly. Even at very low 40 or 50 ma. I forget how low I went before the readings started to skew but I couldn't say if it was my Rigol equipment or the meter.

However, for what I need it for, it works great. Its rechargable and lasts about an 5-8 hours with the scope function. USB-C and will turn on from a dead battery when plugged in. A little different than my other meter running off a 9v battery for 5 years. I really only want to see a control signal or the quality of a CAN waveform. I have tried to analyze an ignition waveform pattern and its a bit difficult. Anything that is off the screen is gone, there is no scrolling history. Maybe the hantek has that feature? This seems to be a common problem with most if not all Chinese scopes.

So anything I need to really analyze at depth, I will pull out the SnapOn Verus and wait 15 minutes for it to load up. Someday when I have extra credit to blow without giving myself a stomach ache I'll buy a Pico scope for detailed analysis. If you get the hantek, I would love to hear your thoughts on it. I wasn't impressed with a hantek PC scope I had and got rid of which is what pushed me away from hantek. They also seem to use the same case for multiple versions or pieces of equipment so there are areas where clearly there should be a port put instead is covered with plastic. Kind of shows the cheapness of the hantek product. Youtube reviews show that small issue. The OWON feels really nice in my hands. I have dropped it many times and its held up.

The OWON scope and the TopDon Phoenix Smart are the two tools I would like to find time and do a video detailed review on for in the field auto diagnosticians.

Do we not change the title to (FIXED) anymore? I have done that twice and both times it seems to get removed.