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Discussion Starter #1
Hi guys!

I ned Your help, I am not sure 100% what could resolve my problem.

Firstly the parameters of my car:

Peugeot 407 sedan
2.0i RFJ (EW10A)
2006

About the issue:
The cooling fan does not kick in at low speed at all. The high speed operates as expected.
I checked the car with pp2000, no fault codes.
I tried to test if I can turn on the low speed with the pp2000, but without any success. However during the highs peed test the cooling fan kicks in as expected.

When I turn on the A/C the pressure switch clicks and the cooling fan start operating.
I checked also the measured engine temperature and the cooling fan speed command field.
When the A/C is on, the cooling fan speed command value is about 50-60%.
When the A/C is off and the engine coolant temperature is above 98°C the cooling fan speed command field in the pp2000 shows 0%, and the low speed does not kick in :(
When the engine coolant temp reaches 105-108°C, the high speed fan kicks in and keep operating for about 10-20 sec.

I also checked in the ServiceBox when should kick in the low and the high speed stage of the cooling fan:
low speed at 98°C
high speed at 105°C

I checked the connectors around the cooling fan. the connectors and the relay seemed to be OK, no corrosion at all.
The wiring diagram is attached here:
89577



I assume the fuse Nr. F1 and MF01 are fine as well as the relay, because the cooling fan kicks in at high speed and when the A/C switched on.

Other guys say the cooling fan itself is the fault and it should be replaced.

I am thinking about accepting thier suggestion and replacing the cooling fan unit could resolve the issue.
But i am not 100% confident about it and that is why I really need Your help.
A new cooling fan is not a cheap thing, so I do not want to find myself in a situation where I buy a new cooling fan for 300Euro and replacing it does not fix the issue.

I would really appriciate if You could help me with your knowledge and experience.

Thank You for reading this post and for making effort to help me out :)

Best regards,

Matyas
 

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Discussion Starter #3
Fan wiring loom is a known issue on the 407
Thank You for the answer!

Do you mean the wiring loom coming from the BSM/fuse box or the wires connected directly to the fan's control unit itself?

How could I measure if the wiring loom is OK or not?

I am not sure about what type of signal coming from the BSM to the fan's controller (wire Nr. 1540). Is it a PWM signal or just a voltage level?

Other question, when A/C is turned on should the cooling fan run at full speed or low speed or the BSM modulates its speed according to the motor load?
 

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Discussion Starter #4
UPDATE

I checked the control wire (Nr. 1540) coming from the motor controller to the fan's controller. The control signal is PWM. When the high speed test was running from the pp2000, I saw a correct PWM signal on the control wire. When I turned on the A/C the result was the same.
Now the interesting part, when I run the low speed test with the pp2000, there was not any PWM signal on the control wire (Nr. 1540). Very interesting.

I assume the cooling fan is fine as well as the wiring loom. There should be some isse with the motor controller itself.

What do you think?

Is it possible to fail the motor controller in this way?

Is there any chance to replace the motor controller with an used one?
 
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