New Device, Immediate Issue: Troubleshooting Guide

Hello, I'm new here and wanted to briefly introduce myself. I live near Marburg and am 25 years old. I have two TDIs at home.

My problem is that I had my VW T3 converted to a TDI engine. It's a TDI from a Sharan, specifically an AFN engine with 110 horsepower.
"I don't have a diagnostic connector, an OBD connector specifically. The person who installed this in the bus somehow accessed the diagnostics through a different connector. As you can see in the pictures, it has a green and a brown wire. Brown is ground, green is data. This connector leads to the engine control unit (ECU) for the immobilizer. I'm at a loss as to how I can use my OBD adapter to access this ECU through this connector. Can anyone help me? I also have VAG software to access the ECU. With my Passat, which has an OBD connection, it's not a problem. The engine was only sold for conversion, so the OBD connector is missing. I would be grateful for any help."

Regards, Tins.

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Hello Tins,

sage mal die VAG-Teilenummer der ECU. Got a PM.

Best regards, Rainer.

The data line (K-Line) must be connected to pin 7 of your diagnostic connector. Connect the ground (GND) to pin 4.

In addition, you need to connect a 12V power supply (ignition plus via fuse) to pin 16 of your diagnostic adapter.

Okay, let's check if you're getting a "immobilizer" error and next, whether the "MSG" is working correctly. (The K-line must already have a connection between the immobilizer and the MSG; otherwise, the immobilizer wouldn't allow the engine to start ).

Best regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It refers to a sudden and strong gust of wind.

But the plug in the picture is not a diagnostic plug...

Rainer K. wrote:

But the connector in the picture is not a diagnostic connector...

Oh dear . I blindly trusted Tins that this connector would have GND and data on it...

Nevertheless, my statement above is still essentially correct. He just doesn't need to obtain the K-line from the two-pin connector, but rather either from pin 3 of the WFS (normally) or from pin 61 of the engine control unit (directly). (Fortunately, I didn't specify exactly where he could get the K-line from ).

PS: Now you've made me curious, what's on the two-pin connector?

Hi,

Sure, but what if the connector doesn't have GND (ground) and data pins?
Is this really safe? It's best to check it with a multimeter and a 100-ohm resistor. The data line must carry 12V (when the ignition is on) and should be able to be pulled down to ground with the 100-ohm resistor.

Best regards, Rainer.

Is it possible to take the K-line from the OBD connector and connect it directly to the control unit, or should I use this other connector instead?

Okay, so I traced the cable to the control unit. It connects to pin 2. There's a white-yellow cable connected to pin 61.

The part number on the solenoid valve is 028906021AK from Bosch.

Pin 2 on the ECU would be the tachometer signal.

I was just looking at a wiring diagram for a Golf, and pin 2 goes to a dashboard module with a display. But how does it get from that connector to the control unit? Here are the pictures from his website where it's connected to the connector; maybe this will help http://kfz-werkstattguide.com/kfz-service_torsten_kaufmann/page=free3_page;item=11277.

Hi,

If you paid for the conversion including the diagnostic connector, then they should install a proper diagnostic connector.
As Guste already mentioned, pin 61 on the engine control unit leads to success, but pin 3 of the WFS would be even better.

Best regards, Rainer.

Why is it better to go through the immobilizer system? The immobilizer is a small, square module. Which pin should I connect to? One wire comes from the engine control unit and goes into the immobilizer control unit; is that the pin I need? Best regards.

Tins wrote:

why is it better to go through the anti-theft system?

The original wiring is the same. This allows you to access not only the MSG (Modular System Gateway), but also other diagnostic control units (e.g., WFS - Wireless Front System).

Tins wrote:

The immobilizer is a small, square box. Which pin do I need to access there?

Please read my and Rainer's posts in this thread carefully again. We have even written twice about which pin of the WFS you should go to. Also, please read the "faux pas" thread in this forum and adhere to the usual capitalization when you expect help from us. You did manage it correctly in your first post.

Tins wrote:

One comes from the main control unit and goes into the secondary control unit; is that pin the one that comes out?

No, that's pin 2 of the WFS.

"Sorry, I didn't know about the capitalization. It was just a mistake. I'll try tomorrow to see if I can access the control unit through this pin. I'll let you know if it works."

Regards, Tins.

Why is it better to go through the anti-theft system?

The original wiring is the same. This allows you to access not only the MSG (Modular System Gateway), but also other diagnostic control units (e.g., WFS - Wireless Front System).


@guste100,

Why is that?
To my knowledge, the K-line is connected in parallel to all control units, similar to the CAN bus architecture. Therefore, it doesn't matter where you connect to the K-line, as long as there is no gateway in between.
Sure, I will translate the text from German to English and correct it if necessary. Please provide the text you would like me to translate.

In the pictures of the modification, it can be seen that the diagnostic connector is connected using a 'flying lead' wiring system. The U-Bat connection is directly taken from the battery, which makes it quite likely that this is a level shifter.

He also writes that the diagnostic device can be connected directly to the battery via a 2-pin connector. However, in my opinion, he has cut corners here because the 2-pin AMP connector is quite cheap. A more appropriate solution would be an OBD connector with direct power supply, or if that's too expensive, at least a two-connector system like the one found on the Audi B4.

Best regards, Jochen.

Jochen_145 wrote:

To my knowledge, the K-line is connected in parallel to all control units, similar to the CAN bus architecture.

Almost correct: All ECUs (Engine Control Units) except for the MSG (Modular Sensor Gateway) are directly connected to the K-line. The MSG is only connected to the externally routed K-line via the WFS (Wire Harness and Connector System).

During the diagnosis process, you won't notice anything because the WFS (likely referring to a specific system or component) becomes transparent, allowing data to flow directly from the diagnostic port, through the WFS, and to the MSG (another system or component).

Best regards,
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It refers to a sudden and strong gust of wind.