So here is my problem.

New coolant sensor, new thermostat, new coolant and bled. Car nearly warms up but radiator fan is on from switching the ignition on which is over cooling.

The non air con Stilo 1.2 only has a slow speed relay and fuse. If I pull relay or fuse the fan stops. Multiecuscan shows the fan is always active. Engine temp sits at 71-76 degs (disconnect fan and temp goes to normal 80-85-ish).

I've cleaned up a few (apparently) related earth points but still the same fan runs.

So what am I missing? What could lead to this frustrating electrical issue.

I don't know how exactly your system works.. but i'm guessing it's something like this:
-ECU reads temp from temp sensor.
-if temp is higher than X, the ECU will ground (probably, or send +12v) a relay
-that relay will close a circuit, engaging the fan


Check what temperatures the ECU sees when the engine is cold (should be close to environment temps.

Check if the relay is not stuck closed (they can become stuck almost welded)..use a multimeter.. or better a bulb and a few wires.

How long have you had the car and the problem?

I've used MultiECUScan and it shows cold engine and warming up. With Rad fan disconnected the car gets up to normal temp.

To test the relay T6 (I think on povert spec Stilo) I switched it with the relay that powers the interior heater (same sized/rated relay - and works). Made no difference, fan still runs.

Just remembered last night after a big-ish run the fan did actually stop constant running. Could this suggest an earth thats damp? drying out maybe? Although the big earth point next to the battery has been thoroughly cleaned. I also removed the fuse box from the battery area and checked for any corrosion/moisture (none present).

Or could it be down to sluggish battery perhaps? Its showing signs of age in that some days it can be a little weak on starting.

I had that same problem, I had to replace the body computer. Is there any else that happens? Does it run when the engine if off?

Fan runs if ignition is on, but engine doesn't have to be running.

So where is the body computer located. I'll clean all the contacts in/around the area as it did happen in the past but "went away". Pretty sure this only ever occurs in winter/or when the weather is particularly damp (Summer is usually ok).

Just decided it was about time I fixed it.

Also MultiECUScan shows no errors with body computer etc, all is good.

The Body Computer is the grey box attached to the back of the dashboard fuse box, however it is unlikely to have any effect on the engine cooling fan.

According to the eLEARN wiring diagram, the 1.2 Stilo should have 2 relays for the engine cooling fan.

The engine cooling fan (N11) is controlled by the Engine Management ECU (M10) and relays T6 (low speed fan) and T7 (high speed fan). Both relays have an ignition switched supply to pins 85, and are activated by an earth signal from the EM ECU to relay pins 86.

With the relays removed and ignition switched on, check if there is an earth connection to pins 86 of either, or both of the relays.

I think it's only the early 1.2 with air con that has the 2 fuse/relay setup. My poverty spec 1.2 only had the 1 relay/fuse. Had the car from new so it's not like a previous owner pulled it.

So removing the grey fuse box in the battery compare the showed no dodgy contacts but that's not so say the metal inside the plastic moulding isn't at fault. How easy is it these days to pick up these parts?

I'll try checking for a dodgy earth tomorrow (got a couple of hours without the kids).

Davren said:

With the relays removed and ignition switched on, check if there is an earth connection to pins 86 of either, or both of the relays.

Click to expand...

If your car only has one relay, check if there is an earth to pin 86 of that relay.
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Was going to check today but all that rain out me off.

So to clarify, ignition on I should have no earth on that relay (with cold engine)

StiloBoy said:

So to clarify, ignition on I should have no earth on that relay (with cold engine)

Click to expand...

Correct... remove the relay and check for an earth in the socket that pin 86 of the relay plugs into. Pin numbers are marked on the underside of the relay.
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