Radiator fan not coming on

[gim461]

2009 C4 Grand Picasso.

Radiator fan is not coming on. Engine gets hot going up hill and warning is displayed.

I have the fan out; it has four wires; two large and two small. I have put power on the two large wires; it draws a hefty current but the fan doesn't rotate.

What are the two smaller wires for? Do they need to be powered to make the fan work?

UPDATE I turned the ignition on and measured the voltage on the small wires; they are blue and pink; the pink was about +10V relative to the blue one.

Then we went for a drive, up a long hill; when the temperature warning came on I measured the voltage on both pairs of wires. On the big wires, nothing, so it appears the fan is not getting power. On the small wires the pink was about +12V relative to the blue one.

Thank you.

[wheeler]

Does the fan motor turn freely by hand?
Have you checked all the fuses?
The heavy feed wires normally come from the maxi fuses located underneath the main under bonnet fusebox.

[gim461]

Thanks for your reply. Yes and yes.

[wheeler]

What is the last 8 digits of your VIN & i can look at a wiring diagram?

[gim461]

Hey, thank you so much.

VIN is: VF7**************[VIN obfuscated, can be read by forum staff]. So the last 8 digits are: 9J101622.

[wheeler]

This is the diagram for your car, it shows the motor only has a 2 way connector but you say yours has 4 wires? The fan chopper unit has a 2 and a 4 way plug?
If you disconnect the grey connector on the chopper unit & give power to pin 1 does the fan operate?

[gim461]

Thanks for your reply.

I have attached two pics of the fan, and as you can see there are two connectors, each having two wires. So it seems this does not match the circuit you have posted.

Maybe for this fan, the chopper unit is inside the fan?

Thanks for your help.

[white exec]

Interesting. Does look like a control module integrated with the fan.
Could you post those Bosch item numbers (both the labels), so we can look up technical details for them?
Thanks.

[wheeler]

Thats the wiring diagram based on your VIN. Thats not to say its definitely correct, it does happen sometimes where they are wrong.
I wonder if it can be stripped down further to find a 2 pin connector directly on the fan motor?
Although the schematic shows the fan control module separate they may be integrated.
It does look like a 4 way black which is what the diagram shows on the fan control unit.

[gim461]

Thanks Chris and wheeler.

Attached is a pic showing the numbers.

I took the four screws out of the cover and tried to lever it off, but it I couldn't move it.