Ulfs Adapter: Troubleshooting & Solutions

Hello everyone,

möchte mich zuerst mal kurz vorstellen. Ich komme aus dem Raum Esslingen und fahre selbst einen Audi 100 Typ 44, Bj. 87. Da kann ich eigentlich alles selbst erledigen. So. Gleichzeitig bin ich aber auch Vaters Schrauber am Audi B4 AFN, Bj 97. Und da war dieses Forum schon oft hilfreich. Thank you very much.

Okay, here's the translation:

'Now I have the following problem:'

'On the aforementioned AFN, the most basic adapter barely worked. So, I built Ulf's plug-and-play adapter. And that one doesn't work either! However, instead of using the recommended BC 547 C, I used BC 546 B, and instead of BC 557C, I used 557A. The dealer didn't have anything else... Can anyone tell me if the problem might be due to the other transistors? I've already tried various settings in VAG-COM without success.'

Thank you in advance for your responses.

Regards,

Pure.

Reiner_mit_ei wrote:

At the aforementioned AFN, the most basic adapter barely worked. So, I built Ulf's plug-and-play device. And that one doesn't work either! However, I used a BC 546 B instead of the recommended BC 547 C, and a 557A instead of the BC 557C.

Hi Reiner,

First, please tell us exactly which adapter you built ( "Plug and Play" is not an exact term - which version number is printed on the schematic?), and then we can proceed.

Hi Ulf,

I built the adapter on March 16, 2003.

Regards,

Pure.

Reiner_mit_ei wrote:

I built the adapter on March 16, 2003.

Hi Reiner,

Okay, so version 3.1?

There's nothing to adjust.
If it's not working, the following causes may be responsible:

-> "Very unusual" voltage and impedance levels at the COM port (in which case it should work with most other PCs).
-> Construction defects, cable or contact problems.
-> PC and/or vehicle interface is faulty.

Have you already downloaded and tried the test software from the diagnostic article to see what happens?

"In my opinion, the other types of transistors shouldn't be too critical, but A-type transistors fundamentally limit the adapter's compatibility compared to C-type transistors."
B-types are somewhere in the middle.
The most important thing is not to confuse NPN and PNP types.

Hello Ulf,

I have just replaced the transistors with the correct ones. Now it appears that VAG-COM, when connected to our AFN engine with the adapter, can ONLY access the transmission control unit. With a 1.8L A4 gasoline engine (I unfortunately don't know the exact engine code right now), I can ONLY access the engine control unit and, for example, read out error codes.

I haven't tried the test software yet, but I will.

I don't have another computer available at the moment, but I will test that as well once I have one.

Regards,

Pure.

Reiner_mit_ei wrote:

Hello Ulf, I have just replaced the transistors with the correct ones. Now, it appears that VAG-COM, when connected with the adapter to our AFN engine, can ONLY access the transmission. With a 1.8L A4 gasoline engine (I unfortunately don't know the exact engine code right now), I can ONLY access the engine control unit and, for example, read out error codes.

Hi Reiner,

These selective accesses are usually related to the different logic level voltages of the individual STGs.

Have you installed the DC offset LEDs 5 and 6? Does either of them light up during (an attempted) communication?

The detection threshold in the adapter is essentially determined by the resistor chain R4-R6 and LED4.
Is everything in this area set up exactly as planned?

P.S.: Is the D3 module okay, and more importantly, is it installed correctly? Incorrect installation could cause symptoms like the ones you described.

Otherwise, you could try replacing the R7 resistor with a 22k resistor; maybe that will fix the issue.

Hello Ulf,

Have you installed the DC offset LEDs 5 and 6? Does any of them light up during the (attempted) dialog?



Yes, they are installed. However, they don't light up during the dialogue.




The detection threshold in the adapter is essentially formed by the resistor chain R 4 - R 6 and LED 4.
Is everything in this area set up exactly as planned?


Ja. Ich habe die Schaltung von einem Radio- und Fernsehtechniker durchsehen lassen. Is everything okay?



P.S.: Is the D3 module okay, and more importantly, is it installed correctly? Incorrect installation could cause symptoms like the ones you described.
Sure, that's fine.



Otherwise, you could try replacing the R7 resistor with a 22k resistor; maybe that will fix the problem.
I swapped them out, but there's no improvement. However, LEDs 1 and 2 are now shining a bit brighter.

I've tried the adapter testing software. Everything seems to be working fine so far. During the loop test, the black bar reaches the second-highest mark...

When I try to communicate with the AFN, LEDs 1, 2, 3, and 4 light up sequentially, with LED 2 being slightly dimmer (it's also a slightly different type than the others).

In most control units, the 'VAG number' is still present, but that's all you'll find.

What's suspicious is the fact that I was able to access the transmission (automatic) control unit and read the error memory on our AFN vehicle using both Christian Helm's basic adapter and your adapter, but nothing else. It behaved the same way on the A4 gasoline car. There, I could only access the engine control unit with both adapters, and Christian's adapter worked perfectly for that as well.

Could it be that my laptop is causing problems? As soon as I can, I'll move my old P120 desktop computer into the garage and try again.

Thank you for your efforts, and have a nice evening.

Pure.

Hello Reiner,

Do you really have an AFN in the 80 B4? I thought those were only available with the 1Z engine.

I also have a B4 TDI (older version), and none of the adapters work for me either.
I also built the one with the MAX232 chip, which worked without problems in many other, more modern cars.

@everyone: Does an Audi A4, model year 2000 (facelift), with a 110 HP TDI engine have a different pinout for the diagnostic connector?

Regards,
Lucas.

Reiner_mit_ei wrote:

I had the circuit checked by a radio and television technician. Everything is okay.

Hi Reiner,
Even professionals can overlook mistakes...

Quote:

I have tried the adapter test software. Everything seems to be working fine so far. The black bar in the loop test reaches the second-highest mark...

Okay.

Quote:

When I try to communicate with the AFN, LEDs 1, 2, 3, and 4 light up alternately, with LED 2 being slightly dimmer (but it is also a slightly different type than the others).

Okay, LED 4 should not blink or alternate its light, but it must remain constantly lit. If its brightness fluctuates significantly during operation, something is likely wrong.

Quote:

In most control units, the "VAG number" still "comes across," but that's all there is to it.

Was passiert anschließend? Error messages?

Quote:

What makes me suspicious is the fact that I was able to access the transmission (automatic) control unit on our AFN, just like with Christian Helm's basic version and your adapter, and read the error memory, but nothing else. It behaved exactly the same way on the A4 gasoline engine. There, I could only access the engine control unit with both adapters, and that also worked without any problems with Christian's adapter.

This, in turn, suggests problems in the area of other hardware or software.

Quote:

Could it be that my laptop is having problems here?

Not entirely to be ruled out...
Have you ever tried the special settings described in the adapter article in VAGCOM?

Hello,

Do you really have an AFN in the 80 B4 - I thought those were only available with a 1Z engine?



Oops. I made a mistake. It's an A4, type B5 with AFN.


Yupiii: The adapter is working !!! However, it's not working with my laptop (Gericom P3 800 with Win 2000, SP 4) but with my desktop (P 120, Win 2000, no SP). I spent yesterday's effort packing the 17' monitor into the car...

Thank you so much, Ulf, for your tireless advice. I'm sorry that I spent so long trying different adapters and didn't even check my hardware.

Regarding your question:


'Zitat:' translates to 'Quote:' in English.
In most control units, the 'VAG number' is still present, but that's all you'll find.

Was passiert anschließend? Error messages?



The error message (roughly translated) says: 'Too many communication errors to continue.'

I tried the special settings in VAGCOM using my laptop, but it didn't work. However, when I used my desktop, the adapter worked immediately with the default settings on a B5 AFN and an older Polo.

Could it be that my laptop, or rather its COM port, isn't providing enough 'power'? Or that the adapter has too low an impedance for my COM port? Do you see any way to influence this?


Regards,

Pure.

Hello Reiner,

It could also be due to your Win2000 configuration (this happened to me once).
Disable all antivirus software or other background programs. There used to be a patch for Internet Explorer that affected the timing of serial communication, and after that, nothing worked anymore.

Best regards, Rainer.

Rainer K. wrote:

It could also be due to your Win2000 configuration (it was like that for me once). Disable all antivirus software or other background programs. There used to be a patch for Internet Explorer that had an impact on the timing of serial communication, and then nothing worked anymore.

Hi Rainer,

See, I had forgotten that as a possible cause . . .
I'll add that to the diagnostic article.

Quote:

Could it be that my laptop, or rather its COM port, is not providing enough "power"? Or that the adapter is too low in impedance for my COM port?

Probably not, because if that were the case, would not be able to have any communication at all.