S1 cooling fans - only one spins

Hi all,

I’ve had a coolant hose failure on my S1 and whilst I had the front clam off to fix it I noticed that only one of my cooling fans ever spins.
I took the connector off the engine coolant sensor as I believe that makes the ECU spin the fans flat out, but still only one fan spins.
I’ve then disconnected the fan in question and applied 12v and it spins just fine.

I’ve had a look through the service and maintenance guide and see that the fans are wired in series for normal cooling or in parallel for higher demand, so I assume I do have a fault?

My next item to investigate will be the fan control module but before I go there I just wondered if anyone had any thoughts or ideas please?


PS - I have checked all the fuses.

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Yeah, with one trigger from ECU the fan control module puts the fans in series for low speed, so both spin but with only 6v so half speed.
Then with a second trigger from ECU the module switches so both fans get a 12v direct feed.
If only one fan is working full speed I would

  • check carefully that both fan connectors are fully engaged and clean
  • check fuse A13 as that powers the half speed circuit-
    If that is all ok then you need to check that you have 12v at the fan module and then check you get the trigger from the ECU for low speed.
    Unfortunately my experience is the wire colours in the wiring diagram and what is in the car are different … go figure.
    The diagram says the feed from A13 is black/brown … mine was just black with some remnant of some brown tape around it.
    The trigger for low speed is indicated as blue/yellow but in my car it was blue/grey which in the diagram is shown as trigger for full speed …
    The module is from an MGF btw
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If that all checks out then you need to test the relays in the module … which is relative easy off the car if you have a 12v source and multimeter.

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Thanks AndyD, that’s very helpful. I’ll work my way through the process and report back!

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