Engine Control Unit (ECU) Not Responding: Troubleshooting

Hello everyone,

I'm currently experiencing a significant problem with my Golf 3 TDI (engine code: ALE). The engine shuts off approximately 1 second after starting. This issue occurred after the car had been parked for about 2 hours. Since then, it hasn't started or run properly. Before this, it was working perfectly.

The immobilizer has the following error code:
00546 027 Data line fault / implausible signal.

Furthermore, my engine control unit (ECU) is not responding to VAG-COM or other diagnostic tools.

"The data cables have already been checked for continuity. The engine control unit (ECU) is also receiving power. The immobilizer control unit (including the reading coil) has also been temporarily replaced, but so far, nothing has worked."

Does anyone have any ideas? Is my engine control unit (ECU) broken? Does anyone know of a junkyard that has an ALE engine ECU, or can I also use ECUs from an AHU or AFN engine?

Freggel wrote:

The engine turns off again approximately 1 second after it starts.

Typical of a "spicy" WFS.
Therefore, the areas of the MSG that are at least allowing the engine to start are functioning correctly.

Quote:

The immobilizer has the error code: 00546 027 Data line fault / implausible signal. Furthermore, my engine control unit (ECU) is not responding to VAG-COM or other diagnostic devices.

The data lines have already been checked for continuity.
If all of that is actually true and the wiring (K-Line!) is okay, then your MSG might be faulty.

That's extremely rare. Cable problems are much more common.
That the WFS remains active and the MSG is not accessible via diagnosis, both can be conclusively explained by a single defect in the K-line. I would thoroughly investigate that area before spending $$$$ on an MSG, which might not even solve the problem.

Good luck with your search...

The immobilizer has the error code:
00546 027 Data line fault / implausible signal.

Furthermore, my engine control unit (ECU) is not responding to VAG-COM or other diagnostic tools. The data lines have already been checked for continuity.

The MSG is addressed by the WFS. In new vehicles, the WFS is integrated into the instrument cluster (IC). In the case of the G3, it would likely be a separate control unit located under the steering wheel.
Given that the vehicle is displaying error messages indicating a blocked WFS (Windshield Washer System) and the WFS is reporting a K-Line issue, I suspect a simple cable break in the K-Line between the WFS and the MSG (Modular Service Gateway). This is a fairly common occurrence!

First of all, thank you very much for your quick responses.

Hab die Datenleitung mittlerweile bestimmt schon mehr als 10 mal durchgemessen, da besteht zweifelsfrei Kontakt. Das WFS-STG ist hinter dem Kombiinstrument versteckt. Die Datenleitung geht von der Zetralelektrik zum WFS-STG und von dort zum MSG. Hab sogar schon das WFS-STG ausgebaut und die Datenleitung dort gebrückt. Even without success.

As the next step, I wanted to install my MSG (Modular System Gateway) into a different vehicle and attempt a diagnosis there. The options I'm considering are a Galaxy from 1999 with an AFN engine, and a Passat from 1995 with either a 1Z or AHU engine.

What do you think? Which vehicle would you recommend to me?

Sure, here's the translation:

"Thank you in advance."

Best regards, Freggel.

Freggel wrote:

I've even expanded the WFS-STG and bridged the data line there.

Even without success.
Hm, that actually seems to be slowly pointing to an error in the MSG within the K-Line interface .

Quote:

As the next step, I wanted to install my MSG into a different vehicle and try to perform a diagnosis there. The options are a Galaxy manufactured in 1999 with an AFN engine, and a Passat manufactured in 1995 with a 1Z or AHU engine. What do you think? Which vehicle would you recommend to me?

I can't tell you which vehicle would be better suited... but while you're at it, you could install the other car's module (MSG) into yours.
If it becomes addressable through diagnostics, then unfortunately, in 99% of cases, it's due to your engine control unit (ECU).

Freggel wrote:

I've probably measured the data cable more than 10 times now, and there's definitely a connection.

Yes, there might already be a connection. However, have you also checked to make sure there is NO contact with any other wires? For example, the insulation might be worn through, causing the K-line to have contact with ground. In that case, you might still have a good connection between WFS and MSG, but communication would still not be possible. I would therefore suggest disconnecting the K-line at the MSG and connecting it directly to a diagnostic tool (also disconnect the old K-line there).

Freggel wrote:

As the next step, I wanted to install my MSG into a different vehicle and try a diagnosis there. The options are a Galaxy manufactured in 1999 with an AFN engine, and a Passat manufactured in 1995 with a 1Z or AHU engine.

However, it's probably faster to simply install the MSG (as you already suggested) in a different car. It should be compatible with both vehicles and accessible via diagnostics.

It would be the first MSG where only the K-line was shot, according to what I've read in this forum. I consider problems in the wiring to be much more likely.

Regards,
Sure, here's the translation:

"Guste" is a German word that means "gust" or "gust of wind." It can also be used to describe a sudden burst of something, such as laughter or anger.

Thank you very much for your numerous responses.

I have now installed the MSG in the Passat (1Z). A diagnosis was also not possible there. Now I have sent the engine control unit for testing... let's see if it is defective .

Thank you very much, best regards, Freggel.

The MSG is indeed defective. However, the company to which it was sent could not repair the MSG because the ERP module is also defective, and the company does not have the necessary software.

So, my advice to everyone who wants to submit an MSG file: Ask beforehand if the SW (software) is available. This will save you a lot of trouble and effort.

I had to buy the MSG from the dealer for almost €1000.

Thank you again.

Best regards, Freggel.

Freggel wrote:

The MSG is actually defective. However, the company to which it was sent could not repair the MSG.

Wow, a real exotic among the bugs... my condolences about the cost .

Do you know if the MSG (presumably a piece of equipment or a location) has ever been damaged or experienced problems like a power outage, flooding, etc.?

Thank you for your insult, Ulf .

The MSG was only poorly treated in that the voltage while driving with the worn-out carbon brushes of the alternator was not necessarily constant. The screws (painted) on the MSG were still original, so no one had tampered with it. However, if the voltage was unstable, the internal voltage regulator of the MSG should have failed. But that one is still okay.

I can imagine that an EEPROM would only survive a certain number of write cycles. With memory sticks for PCs, which are also based on similar rewritable chips, a finite number of write and read cycles are also specified.

To the best of my knowledge, the MSG adapts to the driver's individual driving style, meaning an adaptation value is stored in the Erpom (please correct me if I'm wrong).

The engine and the MSG have now accumulated more than 300,000 kilometers. Perhaps the MSG was adapted too frequently internally .

By the way, the MSG that I bought from the dealer is from the year 1999, so it's definitely not a new part. I still had to pay almost 1000 € for it, even though it's a popular item.

Best regards, Freggel.

Hi Freggel,

First of all, my condolences.

Since I only just stumbled upon this thread, I'd rather not comment on it.
Okay, I don't want to depress you any further.

Please forget about write cycles immediately.
The EPROMs (which is the memory where the program and calibration data are stored).
With these old devices, the programming is only done once - during the manufacturing process.
The EEPROMs, in which, for example, the error memory is stored, are written to more frequently.
According to the manufacturer, each memory cell can be overwritten more than one million times.
will be achieved, even in older cars (at least, I don't know of any that do).
I don't like it because it's not written cyclically; the worst-case scenario involves counters for each error entry.
which increase with each vehicle start - but 1,000,000 starts with a pending error???).
Self-adaptation does not exist in older TDI engines (I'm not sure about EDC16 and Simos PPD).
Therefore, deleting channel 0 has no effect.

Best regards,
Rudi

Thank you for the information, Rudi.

However, I always felt that after a period of fuel-efficient driving, my TDI felt slower, and it would only accelerate strongly (and uncomfortably) again after a few kilometers of more aggressive driving. This was probably due to carbon buildup in the turbo. That's why the idea of adaptation came to mind.

Thank you, and best regards, Freggel.