Peugeot 407 Cooling problem

[lulupapa]

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 diagbox, no fault codes.
I tried to test if I can turn on the low speed with the diagbox, 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 diagbox shows 0%, and the low speed does not kick in
When the engine coolant temp reaches 111°C, the high speed fan kicks in and keep operating for about 10-20 sec.
When the engine coolant temp is above 105°C, after turning off the engine it does not kick off the low speed to cool back the engine.

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:

(https://ibb.co/G3rS90W)

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.

I measured the control signal coming from the motor controller using an oscilloscope.
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 diagbox, 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 diagbox, there was not any PWM signal on the control wire (Nr. 1540). Very interesting.
And the most interesing thing is when the engine temp reaches 98°C, the motor controller doesn not send an increasing PWM signal to the cooling fan controller (commanding the ecu of the cooling fan to start spinning), neither at 108°C. It only sends almost a full PWM signal to the fan when the motor temp reaches 111°C.

I assume the cooling fan is fine as well as the wiring loom. There should be some isse with the motor controller itself.
Can't figure out why does not send the motor controller control signal to the cooling fan above 98°C.

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?


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

[veress1991]

Hello Matyas,

I have similar failure the engine fan is not working.
I measured relay it works properly.
I have not measured pwm signals yet, but I would like it.
How did you solve the issue? Could you give some advice me?

Regards,
Gabor

[ozvtr]

The fan motor has an integral speed controller in it and these speed controllers are problematic.
It's not really a good idea to put semiconductors in a hot air stream I.E. air coming off a radiator!
There are a lot of different failure modes but they all come back to the electronic speed controller.

You can buy new complete fan assemblies aftermarket or there is this mob that offer repair kits for the motor/controller:
https://electrorefit.com/product/peugeo ... fter-2002/

You could replace the motor/controller from a breakers but it may also fail in the future!

[veress1991]

Thanks ozvtr your answare, my fan looks like failed.

Meanwhile, I tested another one (reference) and it works fine in high speed but in low speed it does not work. The relay works properly checked externally. The test was performed with Diagbox.
This one has 2pcs connector like lulupapa's circuitry diagram at below.

Unfortunately, my fan has 3pcs connectors. One power supply and two another, (407; 2004; 2.0 HDi RHR 100kW).
I attached a picture:

Connector of original fan

So, I connected the reference fan on the car's cable harness, see below picture:

Reference fan connected to car's harness

In this configuration the fan works in high speed mode but low speed does not. Unfortunatelly, I could not find with my car compatible fan on market yet.

So, my questions is:
Have anybody schematic for 3pcs connector configuration?

[GiveMeABreak]

Please just attach your images using the full post editor, then select attachments and then add files and place them.

[ozvtr]

I am not sure but I assume there is a second fan for the inter-cooler? That's what the second 3 pin plug will be for I guess. I don't know anything about the inter-cooler fan so I can't help you there , sorry.

I don't know how you plan to fix this (repair or replace) but if you plan to replace the motor from a wrecked vehicle you need to make sure the wrecked one has the motor/speed controller unit suitable for your car! There are a lot of different ways the cooling fan speeds are controlled and not all are compatible with your car! Very generally speaking, only the cars with air conditioning seem to have these variable speed type thermo fans.

The fan assemblies can be pulled apart and you can replace/repair just the motor/controller.

Watch the videos on the Electrorefit site. It shows you what the motor/speed controller looks like and how to remove them from the fan assemblies.

The three wires usually associated with the cooling fan are Mauve, Yellow and grey. Sometimes the grey looks like white and the Mauve looks like pink.

The middle pin of the 3 pin connector will be the fan speed signal (yellow). High (12V) fan off. Low (0 Volts or open circuit) will be fan full speed. Pulsing (hi-lo) is intermediate speed.

The fan controller also "reports back" to the engine ECU on pin1 (mauve) of the 3 pin connector. Fan good = 12V. Fan bad = 0V.

[veress1991]

I watched videos on Electrorefit site and I did not find my connector setup.

I read a new DTC code:
P2520 : cooling pressure signal
Characterisation : open circuit or short circuit to earth.

This code has appered after I installed reference fan. Furthermore, when I start A/C, the fan does not start.
I guess the plus connector is related with A/C.

I search a used one, if I will not success I try to repair it.

[ozvtr]

Whoa!! What is the ACTUAL fault here??? Why where you looking at the cooling fan in the first place??
What is your car doing or not doing for you to be looking at the cooling fan??

Are you looking at the cooling fan because the car engine is over heating? Or is it because the air conditioning is not working? No one just pops the bonnet of their car to see if the cooling fan is working! There has to be a symptom.

If you are looking at the cooling fan because the air conditioning is not working, then the P2520 fault is your problem! You have low refrigerant level in the aircon system! The entire aircon system will shut down and the fan wont run. The fan will still operate for the engine. The cooling fan speed is directly related to the "high side" refrigerant pressure. High pressure, high speed. Low(er) pressure, low speed. In fact if the refrigerant is below a certain pressure the fan wont operate at all... for the air con. But will still work fine for the engine.

While there is a possibility of two faults at the same time...it is highly unlikely.

The "low speed cooling fan test" in LEXIA is problematic. On some cars it works and on others it doesn't. I don't know why. A faulty cooling fan will shut down the aircon system but if it still works for the engine cooling, it may be OK. May! be OK. As I said in a previous post, the fan speed controls have multiple failure modes.

You are going to have to address the aircon issue before you can look at the cooling fan. Particularly if that's the reason why you were looking at the cooling fan in the first place!

The P2520 is not related to the "reference" cooling fan, it's just co-incidence. The P2520 is low pressure in the system or a faulty pressure transducer/wiring. A loss of refrigerant is the most likely cause.

[veress1991]

Sorry, my reference fan is good for my car. Yesterday I assembled it and works as well.
I misunderstood roles of connectors. The another connector is for A/C.