Hi all, apologies if this is in the wrong section but I have only ever done a couple of these and i thought this might be of help to somebody in the future. My 2011 MY 2.2 HSE auto was over heating whilst trying to reverse a heavy trailer up a muddy track. The temp gauge went to max and a red light came on. After turning off and letting it cool down i was able to get to the top of the hill. Once on tarmac all seemed OK until i reached a hill when it lost power and the engine performance message came up. Once home i plugged my icarsoft machine in (purchased for a previous problem) I started looking through all the many faults for any thing to do with heating. There was one which said State Current P0480 Fan 1 Control Circuit. I Googled it and didn't come up with any info so looked a bit deeper. Whilst stationary and revving it up I could see the temp gauge rising but the fans didn't come on, even when the engine was very hot.



After turning off I checked the fans could spin freely, removed the large plug to the fan control unit / relay. All looked dry and OK in there, I then checked the fuses all looked good there. Obviously the the two big connections are for the power to the fans which meant the the little purple one goes to the temperature sender. There was a healthy voltage across the ends of the terminals in the plug for the fan power, I then checked the voltage for the purple wire which was zero. I looked for a temperature sender unit but can't find it, I still can't see it. I was looking for some way of connecting the purple wire to 12v to see if that kicked the fans into life but wasn't able to think of a way without also connecting the plug which meant that the purple wire would also be connected and i’m not sure where it goes at the other end.

I then started thinking that the purple wire shouldn't read zero even if the temp sender is starting to break down there should be a small voltage. After rechecking that i thought its probably a loose connection at the other end. Still can't find a temperature sender unit. The cables are bound together with insulation tape so i thought id have a look for a defective cable. It was quite easy to remove this tape till you get the the bottom of the engine bay where it is joined by more wires spliced into the loom. After undoing about 8inches of tape i found a small defect in the sleeving which was clearly a break, BINGO



I cut the wire there, and on stripping back the plug end, this is the easiest end, you could see how the wire had corroded.

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There's no temperature sensor for the fans as such. The fan controller module receives a PWM signal from the ECM, and spins the fans at whatever speed the ECM requests.


Lumpy idle could be anything, but is likely injector related, especially as diesel is now B7 (7% Bio) for which the injectors weren't designed to use.
Stick a couple of doses of Comma Diesel Magic in the tank, over the next few fill ups. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Many thanks for the reply I am going to fill up shortly so will get some of the diesel treatment. Excuse my ignorance but surely somewhere in the cooling system there must be some kind of sensor to read the temperature, a thermistor to vary the readings rather than a switch. Does the ECU send a voltage to this so that as it varies with temperature it can decide how fast to spin the fans ?
Modern cars are a big learning curve !

The engine control module (ECM) receives engine temperature information from the coolant temperature sensor (CTS), and also oil temperature data from oil temperature sensor (OTS), and a fuel temperature sensor (FTS). Based on the these temperatures, the ECM adjusts injector timing and fuel pressure, to maintain efficient running of the engine, through all conditions.

The ECM also broadcasts the engine temperature on one of several data communication buses, so the Ipack will show the engine temperature on the gauge.

The ECM will use a pulse width modulated (PWM) signal to control the cooling fans (the thin damaged wire), using the fan controller module as the power interface.
The ECM will request different fans speeds, depending on the engine temperature, gearbox fluid temperature, and if the AC requests additional cooling.

These cooling system controls aren't really that new, with most vehicles having some form of electronic fan control for the last 20 years. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.

Hi again, thanks for the education, we are never too old to learn ! I'm used to a temperature sender screwed into the radiator or thermostat housing.
I suppose that will be the coolant sensor you described, I wonder where that is located.
I bought the fault code reader for a previous problem and if I'm honest probably aren't using it to its full capacity. It doesn't come with a manual so its a bit hit and miss.
Once again thanks for taking the time to explain.

I understood all models from MY2010 were able to run on 10% bio fuel, certainly my MY2012 had a note in the handbook addendum my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

defendersv wrote:

Hi again, thanks for the education, we are never too old to learn ! I'm used to a temperature sender screwed into the radiator or thermostat housing.
I suppose that will be the coolant sensor you described, I wonder where that is located.
I bought the fault code reader for a previous problem and if I'm honest probably aren't using it to its full capacity. It doesn't come with a manual so its a bit hit and miss.
Once again thanks for taking the time to explain.

The old thermo switch disappeared from radiators from the mid 90s really, unless the vehicle was an old design.

The CTS on the TD4 is in the thermostat housing.

Most FCRs can also give live engine data, so you can actually check the coolant temperature in °C.  Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, my daily driver.
1972 Hillman Avenger GT, the project.