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I'm trying to fix a problem I have with radiator fan #1, it switches on just after the ignition is switched on and stays on at full power and will only switch off if, a) the battery goes flat or b) the battery is disconnected. After reconnecting the battery it will not switch on again until I switch the ignition on.

VCDS is telling me there is an electrical fault with radiator fan#1. I haven't got the log file with me at work but I can dig out when I get home and post the results if needed.

I have ruled out a problem with the fan and inbuilt control unit, I swapped the two fans over and the fault stays with fan#1 - so its something on the cars control that is causing the problem.

Looking at the current flow diagrams in Elsa-win it shows a 5amp fuse (SA9), according to ELSA-Win the fuse box SA is supposed to be in the left side of the plenum - but I cant find the fuse box. Its seems to be a fuse box that is not mentioned in the owners handbook!

Does anyone know where the fan fuse is located? or got another ideas what the problem could be.

Here's the Elsawin procedure for removing the Left Plenum Fuse Box. Look at 3rd picture (number A10-10129) and 5th picture (number A97_10018) only, the rest aren't needed - http://www.ianhenshall.com/Left_Plenum.pdf

It's under the black plastic "protector" at the back of the engine bay which covers the brake servo and is next to the washer fluid reservoir etc.

As to the wiring issue, a permanent "switched live" (i.e. won't switch off but doesn't run as soon as you switch power on) is usually a stuck relay or a transistor inside a control unit rather than wiring. Just to confirm, when you say you've swapped the "inbuilt" control unit, are you taking about the one built into the fan itself or a separate box (J293, Fan Control Unit in the diagram below which looks like this)?



If you swapped J293 then there is only the cars ECU and wiring left but, as I mentioned, wiring alone doesn't normally create a switched Live issue, just a permanent live or a short.

Ian,

Thanks for helping.

I have managed to track down the fuse box and check the fuse, it hasn't blown. Shame as that would have been an easy fix!

Our cars don't seem to have a separate fan control units, they are built into the fan motor, although the current flow diagrams shows them as separate items the Audi part number 4F0 959455F description states fan & control unit. Also the current flow shows a link, but it does not show wiring (circled red).



When I say I swapped the fan over, I meant I removed both fans from the radiator and then plugged fan1 into the wiring for fan 2 and fan 2 into fan 1 wiring. I was trying to prove if the fan/control unit had a problem or if the fault was on the car. So in essence yes I have swapped the control units over. The picture shows the fans once I had swapped them back on to the correct plugs but it gives you an idea of what I was doing.




Track 247 that goes into 45 after the fuse on the current flow goes through a relay (J271), so that will be the next thing on the check list




Then I will the check the continuity of the wiring, my understanding is - there could be a break in the wiring as this would cause the car to go in to protection mode so to speak and switch the fan on.

This is the fault log I took just before I started to strip it down.

Chassis Type: 4F (4F0)
Scan: 01 02 03 05 08 09 0E 11 31 15 16 17 19 36 42 46 47 4F 52 53
55 56 57 5F 62 65 6C 72 76

VIN: WUADA64F39N900412 Mileage: 169350km-105229miles

01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
0E-Media Player 1 -- Status: OK 0000
11-Engine II -- Status: OK 0000
31-Engine other -- Status: OK 0000
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: OK 0000
36-Seat Mem. Drvr -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
47-Sound System -- Status: OK 0000
4F-Centr. Electr. II -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: OK 0000
55-Headlight Range -- Status: OK 0000
56-Radio -- Status: OK 0000
57-TV Tuner -- Status: OK 0000
5F-Information Electr. -- Status: Malfunction 0010
62-Door, Rear Left -- Status: OK 0000
65-Tire Pressure -- Status: Malfunction 0010
6C-Back-up Cam. -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
76-Park Assist -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine (BUH) Labels: 07L-910-552-BUH1.clb
Part No SW: 4F1 910 552 E HW: 4F1 907 552 A
Component: 5.0L V10/4V TFSI ª0040
Revision: F1H05--- Serial number:
Coding: 01050000190F01B0
Shop #: WSC 00191 264 15243
VCID: 2600264391DE4671B3-8072

1 Fault Found:
001152 - Coolant Fan Control Circuit 1
P0480 - 004 - Electrical Malfunction
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 169350 km
Time Indication: 0
Date: 2008.06.17
Time: 03:38:13

Freeze Frame:
RPM: 639 /min
Load: 16.1 %
Speed: 0.0 km/h
Temperature: 98.0°C
Temperature: 63.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.462 V

Readiness: 0110 1001


An earlier scan was also showing "Please Check DTC Memory of ECU Number" and the ABS module which is normal once a couple of scans have been done.


Sunday,02,April,2017,21:06:00:14667
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 17.1.3.0 (x64) HEX-NET CB: 0.4336.4
Data version: 20170320 DS267.7
www.Ross-Tech.com


VIN: WUADA64F39N900412 License Plate:
Mileage: 169350km-105229mi Repair Order:



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 4F (4F0)
Scan: 01 02 03 05 08 09 0E 11 31 15 16 17 19 36 42 46 47 4F 52 53
55 56 57 5F 62 65 6C 72 76

VIN: WUADA64F39N900412 Mileage: 169350km-105229miles

01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: Malfunction 0010
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: Malfunction 0010
0E-Media Player 1 -- Status: OK 0000
11-Engine II -- Status: Malfunction 0010
31-Engine other -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
36-Seat Mem. Drvr -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
47-Sound System -- Status: OK 0000
4F-Centr. Electr. II -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: OK 0000
55-Headlight Range -- Status: OK 0000
56-Radio -- Status: OK 0000
57-TV Tuner -- Status: OK 0000
5F-Information Electr. -- Status: Malfunction 0010
62-Door, Rear Left -- Status: OK 0000
65-Tire Pressure -- Status: Malfunction 0010
6C-Back-up Cam. -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
76-Park Assist -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine (BUH) Labels: 07L-910-552-BUH1.clb
Part No SW: 4F1 910 552 E HW: 4F1 907 552 A
Component: 5.0L V10/4V TFSI ª0040
Revision: F1H05--- Serial number:
Coding: 01050000190F01B0
Shop #: WSC 00191 264 15243
VCID: 2600264391DE4671B3-8072

3 Faults Found:
005715 - Please check DTC Memory of ABS Controller
P1653 - 008 - - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 2
Fault Frequency: 4
Reset counter: 255
Mileage: 169344 km
Time Indication: 0
Date: 2008.06.17
Time: 03:14:54

Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: 24.0°C
Temperature: 26.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 11.049 V

006435 - Please Check DTC Memory of ECU Number 2
P1923 - 008 -
Freeze Frame:
Fault Status: 01101000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 169344 km
Time Indication: 0
Date: 2008.06.17
Time: 03:20:07

Freeze Frame:
RPM: 63 /min
Load: 80.0 %
Speed: 0.0 km/h
Temperature: 24.0°C
Temperature: 26.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 8.509 V

001152 - Coolant Fan Control Circuit 1
P0480 - 004 - Electrical Malfunction
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 169344 km
Time Indication: 0
Date: 2008.06.17
Time: 03:20:09

Freeze Frame:
RPM: 1387 /min
Load: 39.6 %
Speed: 0.0 km/h
Temperature: 24.0°C
Temperature: 25.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 9.779 V

Readiness: 0010 1000

I have now checked every fuse, relay and wire and every thing checks out right up to the Engine Control Unit.

It looks like I have a problem with one of the Engine Control Units (J623)....

Thats a massive pain! Have you got a "spare" you could borrow to check it is faulty before getting a new one?

Yes, a fellow rs6 owner was having some work done and kindly lent me his fans yesterday, connected them up last night and still got the problem, so I think that pretty much rules out a fan fault. I'm 99.9% sure the problem is on the ecu#1 (J623)

Done another full wire trace and resistance check, every cable in the circuit right up to the ecu plugs has a 0.3 ohm reading. All fuses check out ok and I have swapped every relay for another of the same type from different circuit.

Wish there was some way to test the ecu!

Found a guy in Portsmouth that can supply a brand new ecu, flashed with the data from my ecu. He'll transfer all the immobiliser settings and as I have the MTM tune he will also take the EPROM from my old ecu and swap that into the new unit. With 12 months warranty all for £400. Can't believe I the ecu is half the cost of one fan! Almost think it's worth a shot.

Although I want to get the MRC MAP + GB MAP and I think they may have a problem due to the MTM. So considering getting the new ecu with default factory tune, then the local MRC guy will have a clear run at mapping it. I've got the aquarist water meth system which I've still not got round to fitting, I can get that fitted and then have it MRC mapped.

I'm going to get on the Ross tech forum and find out if VCDS is able to perform the "replace ecu function" or if it's a VAG diagnostic function.

What do you think?

Just realised you meant spare ECU, no I've not got a spare. And I think I might have problems due to the immobiliser

Yeap it was the ECU I was on about. As the fan starts with the ignition on rather than the engine running I was hoping the Immobiliser wouldn't be an issue as I "think" the ignition still works when the immobiliser is on, but I'm not 100% sure.

It turned out to be a water damaged in the master ECU. It was not sealed properly by MTM when they mapped it and opened the ECU to change the EPROM

I am having to replace both ECU's as a pair, I'm having the data transferred from my ECU's to the new ones, there are going to be defaulted to the standard factory tune. I am then having the MRC engine and gearbox map installed by their agent here in the UAE, the silver lining to the rather expensive cloud

For anybody that is looking at this in the future with the same problem you can pick the thread up over at Ross-tech forum.

http://forums.ross-tech.com/showthread. ... #post93129

I think you'll be much happier with the MRC tune but I'm amazed MTM's poor worskmanship, wow!