Problem could be in the ecm it send power to the cooling fan.let audi dealership check it out.your cooling fan is ecm controlled.
Not sure myself here as i only get the the older cars to work on but whatever is causing the fault it must have a relay somewhere along the line so its just a case of finding it ,then working out the fault as to why its on ,if its a problem as someone suggested then its easy enough to cure and thats to fit a old fashioned type radiator switch in the top hose with two thin wires soldered to it and bring these wires out under the clip on the end of the hose it will not hurt anything or make it leak then use these wires to the relay to turn the fan on for slow speed which is all i would think you would need 99% of the time and then a manual switch for the high speed ,This repair shouldnt cost the more than a rad switch and a bit of wire and a switch for the high speed ,Now who needs to know how to repair the ECU or even replace it ,Please remember an old thing i learnt or was told many years ago and that is to be cowboy you have got to know how it works to start with to be able to effect a bodge or quick repair .
This year has a engine cooling fan controller module. It is not any of the relays in the power distribution box or fuse center. The controller is told to turn on and off by the Powertrain control module (computer). I think the other expert may not be familiar with this year and model. As to the module I suggest you have the system scanned, a defective controller will set a fault code. Defective wiring is very unlikely to be the problem. Not sure if the US part will be the same, this model was not sold in the USA until 05 I think..
Her is how the cooling fan system is operated.
Details of the Circuit
The cooling fan relay coil receives the Ignition Voltage directly.
The relay is regulated by grounding the control circuit via the driver or the internal switch, a process which is entirely controlled by the ECM.
The driver has been specially devised to supply the ground for the component being controlled.
The ECM monitors the fault line which every driver has.
When the ECM is commanding a component ON, the voltage of the control circuit needs to be low (near 0volts).
When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage).
Hello
It seems this model may have special relays rather than a module, if so the relays are under the dash in the fold down special relay center, there are two relays, one is for low speed fan operation, one is for high speed operation.
Just a nmote this cooling fan staying on problem is common with many models of Audi's. It seems the low speed relay is the most common culprit.
If you do have the fan control module system then it should be bolted to a driver side vertical frame member near the side of the radiator.
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Trace wire from fan to ground if pulling relay doesn't stop fan.
I looked it up on Autozone.com's website, but they just have Audi A4's listed for 2005 model year. Is this in the U.S. or abroad?
I looked up A3 for 2003 model year, but they still only have a4, a6, or a8 for U.S. consumption, which is where I am.
You could still pull apart the looms and see if there is worn out insulation somewhere where it is shorting out to ground or check out the socket ends to make sure there isn't a melted connector or shorted out connector within the plastic receptacle where it connects to the fan.
Being in the U.S., I cannot say whether there is a thermo switch or fan control module box on the Audi A3's. Good luck on your repair.
Maybe purchase a Haynes or other brand service manual for your vehicle in the UK.
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Thanks for your reply duane, ill try that now, do you know if there is a thermo switch on the radiator or is it all controlled from the fan control module box on the audi a3's
its an audi A3 2003 plate. Car bought in the uk.
audi 80 1994 model
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