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?
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
I finally got back to looking at this today.
I went through the process you sent and eventually ended up at the fan control module.
I opened the unit (who thought all those little black clips were a great idea!) and found one relay not conducting when it closed. Its contacts were blackened, i’d guess due to arcing/age/both.
I cleaned it all up with a little emery paper and contact cleaner and its back in the game!
To test it all I left the small connector on the fan control module disconnected and applied 12v to pin 1 and gnd to pin2 (to simulate the ECU requesting low speed fans) and both fans now spin
To test the high speed fans I applied gnd to pin3 and this made one fan spin - initially I though I had another fault but I then guessed that the ECU would gnd pins 2 & 3 at the same time for high power, is that correct please?
I hope so as with 2 &3 at gnd I have two high speed fans running.
I also took the liberty of grabbing a spare module off ebay for £20 - thanks for the heads up its an MGF part
Yes, the ECU will earth low speed first and then high speed, so both must be switched to earth for high speed to work.
This is how I have my MOTEC ECU set up using the control box and it works perfect.
Thanks very much AndyD and i’d say my cooling issues are all sorted now!
I’ll carry on with all the other little other jobs than need doing whilst the front clam is off and hopefully have her ready for a late summer track day!!
