Radiator cooling fan problem

[Norfolkchris]

I have recently bought a 2008 A6 3.0TDi quattro. The car drives perfectly but I noticed that cooling fan 2 (drivers side - V177 in circuit diags) was running continously at high (I guess max) speed. It came on as soon as the ignition was switched on - even without starting the engine - and remained on permanently until about 30 secs after the ignition was switched off. This is annoying because it is very noisy and also runs down the battery fairly quickly if the ignition is left on for any reason.

I checked the car with VCDS and got the following fault.

001684 - Fan 2 Control Circuit
P0694 - 001 - Short to Plus
Freeze Frame:
Fault Status: 01100001
Fault Priority: 0
Fault Frequency: 4
Mileage: 226655 km
Time Indication: 0
Date: 2013.05.18
Time: 12:54:13


Freeze Frame:
RPM: 0 /min
Torque: 0.0 Nm
Speed: 0.0 km/h
Duty Cycle: 9.9 %
Voltage: 11.17 V
Duty Cycle: 9.9 %
Duty Cycle: 9.9 %

I also used the output tests facility of VCDS to confirm that the other fan (V7 in circuit diags) is working correctly- I just had not seen it come on previously because I guess that there was no call for it with fan 2 already running. Fan 2 does not respond to the output tests - just continues to run at max speed all the time.

Looking at the circuit diags I noticed that the power supply to the two fans are fused separately. As a temporary measure I have removed fuse S104 (Drivers side plenum box) to disable fan 2. Fan 1 now cuts in as and when required and fan 2 remains off as expected as it has no power.

I am hoping that someone may be able to help me with a couple of questions.

1. Does fan 2 have a specific purpose or is it just to supplement fan 1 in hot conditions (for instance). I have seen some mentions on forums that it is required for the aircon - but I don't think that this is the case as the AC is working fine without it.

2. Does anyone see a problem running without fan 2 for a while (except the possiblity of overheating in extreme conditions)

3. Does anyone have a view on the likely cause of the original problem and/or exact meaning of code ? Obviously the fan itself works so I would suspect the fan controller for fan 2 but if this was faulty (ie stuck in on - high speed) would the fan not continue to run all the time even if the ignition was off ?. Could it be a problem with the ECU itself ? There is a plug / socket in the control wiring between the ecu and fan controllers in the plenum box - could I do any measurements or testing at this point to diagnose the exact fault ?

Any help gratefully received.

Chris

[MarkTM]

I believe there was a recall to fix by the insertion of some additional stuff in the drivers side plenium.

I had the fix on mine, but my problem was that the fan wouldn't run at all, diagnosed as a wiring fault after I'd spent £250 on a new fan and controller (luckily not the Audi price of £918 for the same!)

Check with Audi if yours had the fix, just checked my 07 and fan doesn't come on as yours does.

[MarkTM]

PS: welcome to the forum!

[gupsterg]

Hi NorfolkChris :) ,

On the early V6 IIRC it was the control unit / relay which created a situation where the fan ran on ... I have the recall on mine as it is a 2005 V6 3.0 TDi ... Link:- Mysterious relays plenum chamber (http://www.vwaudiforum.co.uk/forum/showthread.php?135721-Mysterious-relays-plenum-chamber)

IIRC if you turn AC to the lowest setting fan 2 should come on straight away ... so I would assume if you disabled it it maybe detrimental but can't be sure :Blush2: ...

It could be the relay/control unit is at fault thus fan running on :dunno: ...

If you have access to the wiring diags, you must be able to see the TSB's?

I will PM you my external email as you can't PM member's at mo :) ...

ATB
G

[Norfolkchris]

Thanks for your replies.

I bought a copy of Elsawin on Ebay which is why I have access to the wiring diagrams - maybe the TSB's are available there. I will have a look. Do you happen to know the exact condition that the recall was meant to fix - I'm thinking that if it applied to 2005 cars then they would have fixed the problem by 2008.

I am hoping that someone out there may know how to test the signal from the ECU to fan 2 - that way I can pin down whether the problem is with the controller or on the ECU side of the connection. I need to establish whether the fan is running because it is being told to do so by the ECU or because there is a fault in the controller that is causing this regardless of what the ECU is trying to do. There are three wires in the relevant connector in the plenum chamber - I assume one signal for each fan controller and a ground but I don't know this for sure. Is it possible to measure ECU signals directly with a multimeter ? Any info about how to do this or where to look for further info would be useful - I don't want to fry the ECU by metering the wrong thing.

I am keen to pin down the exact fault before I start changing parts because accessing the fan and controller looks like a major job (Most of the front end has to be removed I think - unless anyone has done it and knows an easier way) which I would hate to undertake without being certain that it would fix the problem.

Finally a question on forum etiquette - I see many mentions of using PM's rather than posting directly on the forum - is there a particular reason for this ?

Thanks

Chris

[MarkTM]

I know that my 07 had the fix as when diagnosing my problem the Indy when opening up that area stated that additional relays had been added as per the recall.

As I didn't actually experience the problem (the one I had was of the fan not working at all and the engine overheating) I did a quick google.

AC Blows Hot Air on Sides, Cold in Center - AudiForums.com (http://www.audiforums.com/forum/audi-a6-9/ac-blows-hot-air-sides-cold-center-106972/)

IIRC not the problems you are experiencing and shouldn't apply to your 08...so a red herring.

Good luck!

[Furion]

I had this problem it cost a few hundreds of pounds to replace all the fans fortunately it was done on warranty, wether or not all the fans needed to be replaced is another conversation however I doubt Audi Warranty would have authorised the work if it wasn't genuine


FURION

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[claudiur]

I have a problem on fans at my car audi a6, 2.7tdi,2009, engine CANA. when i switch ignition or star engine after 20 seconds the big fun run at full speed.it run all time and after switch off engine it shutdown after 30 seconds.i check fans manualy and work perfect. i have 2 errors:1. coolant fan control circuit 2:electric malfunction P0481. and 2. fan 1 control circuit: short to plus P0692. i visited more services and everybody say change both fans but i check them and its ok. Please help me with an idea what i can check? i check voltage on jack. i have 4 wires in jack. 2 big (+ and - permanently) and 2 small, 1 from ignition and apear voltage when switch ignithion and other one small which have 12-13v when fan run at high speed. Normaly on that wire i must have 1.2 when its close and 1.7-1.8 when start to run at low speed.(i check this on second fan from AC). Please help me! how you fix the problem?

[royclark]

Could it be a faulty relay not turning off ? I think mine is -


9-slot relay carrier, behind driver storage compartment




**
-
Fuses on bottom of onboard supply control unit

[claudiur]

Please you can help me with a photo? I dont understand very well the location to check. Thank you very much

[royclark]

Please you can help me with a photo? I dont understand very well the location to check. Thank you very much

I have just taken the information from a wiring diagram, not sure where it is.

[claudiur]

I study but dont know where can be. If somebody can help me plase?

[H_MAGIC]

HI, I had the same issue once I put my car back together, it turned out the electrical connectors were connected wrongly.
My mechanical friend assured me it was impossible to connect the connectors wrongly but I proved him wrong. :D. (well himself wrong as he wired them back in himself)

apart from that have a read here

Radiator cooling fan running for no reason (http://www.vwaudiforum.co.uk/forum/showthread.php/150974-Radiator-cooling-fan-running-for-no-reason)

The relays are in the plenum chamber.

Please Help, water in footwells! - AudiWorld Forums (http://www.audiworld.com/forums/a6-s6-c6-platform-discussion-58/please-help-water-footwells-2828279/)

I believe its the fourth relay on the far right your after.

As for the pins out your after, I think they work of the relays. so best to start there.

But I maybe wrong.

[claudiur]

i see more persons have similar problem with fans on audi a6 c6, nobody fix it? what they do?im sure its an electrical problem

[gupsterg]

Could it be a faulty relay not turning off ? I think mine is -


**
-
Fuses on bottom of onboard supply control unit






Please you can help me with a photo? I dont understand very well the location to check. Thank you very much

What Roy there is highlighting is the relays for the auxiliary heater. I don't think you have aux heater? do you have a module 18 in VCDS log.

I will PM you link showing the module with the relays Roy highlight.


Different auxiliary heater versions are available. Heed the exact assignment when replacing an auxiliary heater. Depending on vehicle equipment and production period, vehicles with diesel engine and “auxiliary heater” optional extra may also be fitted with an electric additional air heater.

IMO you may have fault with the control module for the fans. There are no relays between the fans and engine ecu. The fans and fan control module connect to grounds / positives and engine ecu.


i have 2 errors:1. coolant fan control circuit 2:electric malfunction P0481. and 2. fan 1 control circuit: short to plus P0692.

Can you post the DTC log with freeze frame data and someone may have better answer for you.

[claudiur]

This is freeze frame:

001682 - fan 1 control circuit: short to plus p0692-000--

Freeze frame:
Rpm:0/min
Speed: 0.0 km/h
Temperature:37.8c
Mass air/rev:1192.6mg/str
Duty cycle:95.5%
Temperature 849.6c

That temperature i find on chanel 99 from engine module, and seems to be temperature sensor before turbocharger. But i dont have any fault on it. please help me.

[claudiur]

I see for 2 times after i go on a long way, when i stop the fans are off. i was very happy and i think the problem is fixed. but after the car go cold, after few hours when i start again same problem. i go crazy nobody from my city (service) dont know what to do. i know i will fix by my self with your help.!