Can't find this part

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
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Re: Can't find this part

Post by Classik » Tue Feb 12, 2019 8:42 am

And you did well! :thumb:

In the same spirit a mod could maybe rename the thread to make the information more usable?
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Re: Can't find this part

Post by Shoppinit » Tue Feb 12, 2019 10:30 am

Yeah, mod, what you doing? Mod? Mod? Hello? No one home.
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///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
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Re: Can't find this part

Post by Classik » Mon Feb 18, 2019 11:21 pm

So I'm still chasing these @&# codes, admittedly without success yet, but I will crack them as soon as time permits!

As suggested by Shopp, last thing I've done is to open my former controller (the one installed on the car before the change) but unfortunately nothing caught my attention: capacitors look good and do not leak, no bad solder, no traces of overheating component, and sealing was good..
My next attempts are first to check again all the relays (fuses on the side panel have been all checked ok). But I'm also tempted to change the G65 coolant temperature switch (8D0959481B). Am I right to think both fans should run if the engine is getting hot? In my case only the bigger one is triggered. Same thing when activating the aircon, by the way.
As usual, thanks for any comments, suggestions!
RS6 C5 Avant 2003 Daytona Grey
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Re: Can't find this part

Post by Shoppinit » Tue Feb 19, 2019 12:46 pm

There are no relays between the ECU and the fan control units. The fan control units receive a PWM signal from the ECU. The wires for this go via 2 17-pin connectors. Worth checking them for damage / poor connections. One is the red one under the wipers. Not sure where it is, exactly. Maybe next to the ECU box. The other one is a brown connector in the left A pillar. It's more likely to be the former.

It may be that the fan motor is defective. Does it run OK when you do the output tests? Maybe it's dying and only runs at 100% power, which presumably is what the output test does.

They should both run, but I don't know under what conditions. What happens if you set your AC to blow as cold as possible with the coolant hot?

No point changing the temp sender if you log it and it seems OK. It wouldn't cause the fan codes even if it was defective, I don't believe.

I'll try to look at mine to see when the fans run. Not sure it'll get hot enough in the garage.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Can't find this part

Post by Shoppinit » Tue Feb 19, 2019 12:59 pm

So I just had a quick look at mine. The red connector must be in the ECU box. Couldn't see anything else in the plenum chamber.

My fans run from cold. If I put the AC in Econ mode, both fans stop (engine's cold, innit). If turn the AC back on, they both start.

/Looking more likely to be the fan.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Can't find this part

Post by Classik » Tue Feb 19, 2019 9:13 pm

Thanks for continued help Shopp.
So both fans should run when engine is hot or when Aircon is activated.. Well I'll try to get a replacement then for this fan then (4B3959455D if I'm not wrong). It's just that I find it strange that the fan is spinning at full speed and nothing at intermediate settings whilst turning freely by hand, but seems like we (you) left no stones unturned.. I'll do the replacement and report. :thumbs:
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Can't find this part

Post by bilko1 » Thu Feb 21, 2019 12:02 pm

I changed my fan and control unit back end of last year. Control unit came in a couple of days the fan was on back order. Control unit was approx £200 and fan £290. Control unit is a pain to get to, the fan is held on by one self tapper. Check the rubber cover on the bonnet lock (no longer available) as they disintegrate with age and bits fall in to the fan possibly causing the failure.
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Re: Can't find this part

Post by Classik » Thu Feb 21, 2019 4:41 pm

:thumbs: Thanks for the tip Bilko, I'll have a look at the rubber cover.
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Re: Can't find this part

Post by Nobby » Fri Feb 22, 2019 11:40 am

I changed my fan in the end for a second hand one and it worked straight away. Old fan didn’t seem to power up at all, but when I removed it and after a quick dismantle it fired up fine.
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Re: Can't find this part

Post by Nobby » Fri Feb 22, 2019 11:51 am

As bilko mentioned the fan isn’t that hard to get out, but you need to take the bumper off and put the front support in the service position. Remove the self tapper screw, rotate the shroud and the fan comes out the top. If you can get a replacement fan you can disconnect the cable to it and test the new fan without fitting it. The control module and fan connector join under the little black cover by the PS fluid reservoir.
Daytona RS6 Avant
Rule #36 - At least one gear shall be dropped for every tunnel travelled

** NOW AVAILABLE ** C5 RS6 Cambelt Tool kit rental (also fits other models 3.7/4.2 V8 engines)

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Re: Can't find this part

Post by Classik » Sat Feb 23, 2019 12:01 am

Thanks for the posts Nobby, that's very useful and encouraging! :thumb:

I still haven't changed the fan yet, but here's something new : this morning I was in one of those traffic jams where you barely move and do your best to stay calm and relax. Obviously in need of some fresh air I aimed for the Aircon, but I just couldn't start it. It was stuck in economy mode, certainly due to the secondary fan failure and consequently the relatively high engine temperature : from the needles I'd say coolant and oil were slightly above 95 deg. After a while I was finally able to cruise, but despite the temperature being back to normal, I still couldn't activate the Aircon.. Only option to get it back was to switch off the engine and start again, as if it needed some reset. Is that the normal behaviour, or do we agree there's something wrong here? Could that help for my fan fault codes?
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Re: Can't find this part

Post by Shoppinit » Sat Feb 23, 2019 8:49 am

You shouldn’t see the water temp needle move unless the engine temp is way above normal. It’s not a linear gauge. You might have a thermostat issue.

AC won’t come on if coolant temp is too high.

The big fan alone should be sufficient for cooling in the conditions you describe.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Can't find this part

Post by Classik » Sat Feb 23, 2019 4:21 pm

Thanks for the educated response, as usual. ;)

Thermostat, you mean the temperature switch I mentioned a few post before, the one located at the bottom of the front radiator? Or is there another one?
RS6 C5 Avant 2003 Daytona Grey
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Re: Can't find this part

Post by Shoppinit » Sat Feb 23, 2019 5:54 pm

No. Thermostat. It’s mechanical.

So many things wrong here. The temp sensor in front of the radiator is just for the DIS temp reading and is irrelevant to everything, not to mention comically inaccurate.

The coolant temp sensor is behind the engine on the right and fails fairly frequently. The Ecu and AC use the info from this sensor.

The thermostat regulates the flow of coolant into the radiator to keep the temperature constant.

Guess which is the most difficult to replace...
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Can't find this part

Post by Classik » Sat Feb 23, 2019 10:28 pm

Again, you learn every day. Really though this switch was some sort of hardwired trigger installed for redundancy reasons in case the coolant temperature sensor was faulty, so more than just a 'dumb' and inaccurate display sensor...
So the thermostat it is... I really dig its funny UFO shape, except that it's not a ten minutes job indeed. :|
I suppose both issues (the high temp coolant and the secondary fan code faults) are uncorrelated issues, right? (insert face-palm emoticon).
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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