Aften run pump keeps running with new 324

[UrS4boy]

Its a zener diode that has catastrophically failed.

It has been suggested on my home forum posting that the item is a "ZPY27 27 volt Zener diode".

[Avantus]

It was indeed a 27V zener diode.
Went to get one at my local electronics shop for just 0.18€.

Soldered the old out, new in, put it in the car -> fix!

No more constant running, and when putting on contact the pump now correctly runs for 5 seconds.

[UrS4boy]

It was indeed a 27V zener diode. Went to get one at my local electronics shop for just 0.18€. Soldered the old out, new in, put it in the car -> fix!

Good news. Would you mind posting up more details about this 27V Zener diode so others can use your experience to fix theirs (when it fails). (Please)

Here is a spec sheet link for ITT Zener Diodes for futuer reference:

http://pdf.datasheetarchive.com/indexerfiles/Scans-068/DSA2IH00233077.pdf

[Avantus]

It was a 27V 1.3Watt zener diode. When removed the old one also clearly had "27" on it. So with ZPY27 27V zener diode your typical electronics shop will know enough.

Very important to make sure that your new diode is installed in the correct direction.
There is a black ring on the diode and that has to be facing downwards near the transistor it sits against.
Also make sure that on the back when resoldering the joints, you make sure the transistor and the nearest leg are connected. The other leg has to be connected with the resistance on it's left.

Big thanks for the help!

[UrS4boy]

...Big thanks for the help!

Well thank you for pursuing this solution. At least we know how to fix at least one "324" failure mode now. Thank you.

Of course, what we don't know is why it failed in the first place and why it won't fail again.

[quattro-nick]

maybe I have an explanation
look at the wire diagram on post 17,the pump get's a ground from relais j155 (8/87)
the wire on that has a size 1.0
you have the ground on relais j155 (6/31) with a size 0.5
that does not make sense,if you see the relais gives a ground to fan relais j26 with size 0.5 and then the pump with size 1.0 on the same time so at least the ground on the relais 6/31 must be minimum 1.5 size or 2.5
also,i maybe have another cheap solution if the relais still fried
you can replace relais j155 for a normal relais with a double contact like picture
you can make the following connections
bosch relais:30----- 6/31 ground(minimum size 1.5)
87-----5/87a j26 fan relais
87-----8/87 pump v51
85------also 6/31 or another ground point
86------2/30 thermoswitch

so if the thermoswitch close,the relais close and fan + pump turns

the only thing i dont know is that a bosch relais is a straight swap ,i mean,or the contactpins on the right place but you can always make an electrical adapter

[Braeckie]

Bringing up a very old topic...
I have the same issue in my Audi RS2. Cooling fan is running with ignition off. I disconnected the temperature switch F98, but pump is still running.

So next thing to check is the 324 Module.

But where can I find this module in an LHD Audi RS2?
I dismounted the glove compartment on the passengers side (right), but I can't find it there.

Could you please inform me where to find the 324 module?

[Avantus]

The 324 module is underneath the steering wheel. Left top corner.

[Braeckie]

Ok, I found the module 324 in my car (thanks for the advice, Avantus).

I removed the module and indeed the fan stops running.

However, when checking the module, I cannot find anything strange at first sight. No burned connectors, all seems visually normal.
How do you know whether the module is working normally?

Is it very harmfull to drive the car without the module 324?
I need to pass MOT, so I was thinking to go without the module. The engine will not warm up a lot when driving up there. Or is this a bad idea?

See pictures below.

[sal_s2]

It will be fine without it. The main fan should still work when needed without it. If you want to test this, bridge the wiring on the fan switch located on the bottom of the radiator and the fan should run

[Tractor Dave]

It controls the cool down after the engine is switched off. As Sal says, should be fine but if you do a spirited drive, leave the engine on tick over for 5 mins before switching off. This lets the turbo cool down and prevents the oil from carbonising on the bearings. I did a spirited drive up the Brecon beacons with Trist here infront in his S2 Avant. When we got to the top, the fans were switching on and off for a good 5 mins after stopping and you could hear the afterrun coolant pump running all the time.

[Tractor Dave]

If you have an old school tv repair man near you, ask him to test the zender diodes for you and replace the faulty one

[newsh]

Braeckie
I gathered this info a while ago, I’ll repost it here.

[K Simmonds]

Very intereting, useful to me thread, has save me some F'in about. I mananged to stand on my 324 relay while tring to fid an imobliser faut (bulb stay's on the dash with engine running) and wasn't sure what it controlled, now I know I can get away without one for the time being...

Just got to work out why the alarm and central locking works fine as does the engine but I get that warning lamp now the car has been stood, I'll try cleaning the the contacts for the central locking pump first.

[hashluck]

Question on this topic - I have realised driving my ABY S2 this last few months that I have not yet heard the after run pump come on after stopping the engine (but highest ambient temperature to date has not exceed 20 degrees C but it has had some long but relatively gentle runs and I do tend to let the engine idle a while before switching off). The low speed fan works when I switch the AC button on and the 2nd stage fan kicks in when the temp gage hits indicated 90+ degrees so the cooling system is working properly with engine running and sat in traffic etc. and the temp gauge does not creep any higher once 2nd stage fan kicks in. I have noted the top of the radiator gets very hot to the touch if I open the bonnet after stopping and I imagine heat soak could be quite high.

Question is, have i simply not got to the set of circumstances for the after run relay 324 etc, to kick in after switching engine off or should I expect it to almost always come on? Is there a sure-fire way to test? I am ashamed to admit that I must first of all check the relays 324 and 214 are actually fitted but I would still like to understand expected behaviour from the collective here.