VAG-COM Adapter: Ulfs Diagnostic Tool

Hello,
ich habe Ulfs VAG-COM Adapter in der Version 2.4 vom 07.03.03 nachgebaut. Alle beschriebenen Tests zum Adapter sind ebenso wie das nochmalige Durchmessen der Schaltung einwandfrei verlaufen. Ich habe jetzt versucht, meinen Wagen (VW Passat TDI, Modell 3B aus 04.1997, Motor AFN mit 110 PS) mit der Freeware Version von VAG-COM über den Adapter mit einem Laptop zu verbinden. Leider ist mir dies bisher nicht gelungen. Ich habe dabei sowohl die Versionen 'VAG-COM Release 303.1' wie auch 'VAG-COM 208.1' verwendet. Hardwaremäßig habe ich als Laptop entweder ein Escom mit 486DX-100MHz mit 8 MB-RAM oder ein Dell Latitude CPx mit einem 750 MHz Celeron-Prozessor und 32 MB-RAM verwendet. Keine der Kombinationen hat eine Verbindung mit den Steuergeräten des Wagens zustande bekommen. Auch Modifikationen an den COM-Port Einstellungen (Übertragungsrate, UART-Puffer Aktivierung/Deaktivierung brachten keine Verbindung zustande. Im VAG-COM-Test wird das Interface jeweils erkannt, damit hat sichs dann aber. Auch Änderungen an den Einsrtellungen im Menü 'Optionen' brachten keinen Erfolg. Jetzt bin ich doch einigermaßne ratlos. KaCan you just forget about this now?
By the way: The OBD II test in VAG-COM always tells me that the car is not compatible. That program is mistaken. With the Elektor interface, I can definitely read the raw OBD II data (according to California standards) from the engine. However, I would like to use the greater functionality of VAG-COM.
Could you give me some tips on how I can still connect my car to VAG-COM, preferably using the built-in interface from ULF?
Thank you very much in advance for your help.
Greetings.
Max.

Can you also share the error message you received with us?

Actually, assuming everything is set up correctly, there shouldn't be any problems! My hardware is even worse than your 486dx 100, and it runs stably even with a Dino-1Z accelerator card.

Hello,
Thank you for your reply.
Both laptops I am using are displaying the following messages:
After the test in the options menu:

'Interface Status 0, Ready, Fast-Sync No'.

When attempting to access the control units directly or via the automatic search function, the message 'Access denied' appears after each of the first 4 attempts.

'STG is not responding. Proceed? Yes/No.'

During the automatic TCU search process, I also observe that when certain TCUs are accessed, the warning lights in the instrument display illuminate, the temperature and fuel gauges fluctuate, and the digital clock and daily mileage display are reset to zero.

By the way: The 486 laptop runs on Windows 95 2nd Edition, while the Celeron device runs on Windows 2000 Version 5.0 (Service Pack 2). I have disabled all background programs.

I would appreciate any tips that could help me understand the VAG-COM world and make it accessible for my TDI.

Thank you and greetings.

Max.

What settings do you have in the options?

I'm also familiar with the flashing of various indicators, but the resetting of the trip odometer and/or the wobbling of the needles on the gauges is unknown to me! Are you sure that your interface is really working correctly?
I can understand a 'too many communication errors' message, but 'stg is not responding' is very strange!

Hello,
'I haven't seen the 'too many communication errors' message yet. Instead, when I try to directly address individual SRGs, it tells me that they are not responding. However, when using the 'Device Search' option, it doesn't display this error. Instead, the list of found SRGs remains empty (!!).'
Regarding the interface, all the tests described by Ulf were performed flawlessly. Repeated measurements also show no inconsistencies in the implemented circuit. In my opinion, the deviations from Ulf's bill of materials are irrelevant to the functionality. These deviations are: 10k spindle trimmers for VR1 to VR3, and blinking LEDs.
Andreas' loop test also works perfectly.
While testing the circuit, I also noticed that the voltage on the K-line fluctuates between approximately 8 and 12 volts as long as no test or other menu item, such as the SRG search, is accessed via VAG-COM. However, since I only have a digital multimeter, I cannot make more precise statements about the voltage-time behavior.
As soon as I try to perform a VAG-COM test or access a control unit, the potential on the K-line initially reads 12V. Then, the software attempts to establish communication (4 attempts per control unit) with various potential pulses, but it listens and listens and receives no response.
I'm a bit lost.
Greetings.

Sure, here's the translation:

'Oh yes, the options:'
Also zunächst habe ich die so gelassen. Ohne Erfolg. Dann habe ich die Baudrate von 240 auf 1200, 2400 und 9600 erhöht. Ohne Erfolg. Außerdem habe ich die Einstellungen Blk Int, Char Int (bis 9) und KP2-Zeit mal noch oben, mal nach unten variiert. Lewithout success.
Still clueless!

oops


Assuming the adapter is actually correct, that sounds quite strange!
I think we should probably wait for Ulf there.

Eureka!
'Now it's working. I reviewed the replicated interface again and found that if I bypass LEDs 2 and 3 (my car doesn't need the L-line), I get a very good connection with VAG-COM and its functions. I'm now inclined to believe that the problems I described are caused by the turn signal LEDs I installed. Therefore, I will buy some standard LEDs after Easter and solder them in. Let's see if the interface still looks good then.'
Thank you for your tips, Jörg.
Greetings.
Max.

Hi Max,

Did it have any BLINK LEDs?

Okay, then the situation is 100% clear. A blinking LED consists of electronics that are powered by 5 or 12 volts and control the actual LED. Therefore, it behaves electrically like a more or less resistive load that constantly requires varying amounts of current.

An LED, on the other hand, behaves like a diode; it has a certain voltage drop and otherwise allows current to flow.

Since the LEDs in question are part of the circuit, they must actually be LEDs, or alternatively, regular diodes, or simply pieces of wire (although the latter would change the circuit's behavior).

Best regards,

Jan.

@max


See? It works!

Jan6K wrote:

Did you have BLINK-LEDs in it? Okay, then the situation is 100% clear. A blinking LED consists of electronics that are powered by 5 or 12 volts and control the actual LED. Therefore, it behaves electrically like a more or less resistive load that constantly requires varying amounts of current. An LED, on the other hand, behaves like a diode; it has a certain voltage drop and otherwise allows current to flow. Since the LEDs in question are part of the circuit, they must actually be LEDs, or alternatively, normal diodes, or simply cable segments (which, however, would change the behavior).

Hello everyone (and happy Easter).

Jan is, of course, right: In particular, LEDs 1 and 2 must not be flashing components, because the fluctuating current flow "modulates" the data flow from the PC to the car .

It's amazing that the communication with the blinking lights is at least partially working...

Hello everyone.
So, as promised, I replaced the blinking LEDs with regular LEDs today. That's it. The interface is working perfectly.
I would like to thank Jörg, Jan, and Ulf for their support and assistance.
See you soon.
Max.