Audi A4 AFN Bj97 springt nicht mehr an -> MSG kaputt ? | Posts 16+

Rekord81 wrote:

Vorglühkontrolle leuchtet NICHT auf, ebensowenig die Ölkontrollampe.

Was the relay 109 manually bypassed for testing purposes? Or is your troubleshooting still focused solely on the MSG (Main System Module)?

Rekord81 wrote:

Zuhause auf dem Labortisch kann ich keine Aktivität an der K-Line erkennen.

Did you use a pull-up/pull-down resistor, or did you just measure it with an oscilloscope/DMM? I suspect the output is an open collector!

Rekord81 wrote:

Ich geh jetzt davon aus, dass das MSG wohl doch defekt ist, für weitere Untersuchungen fehlt mir das Equipment (und vor allem der MSG-Schaltplan).

I still consider the statement to be reckless as long as the periphery, such as Release 109, has not been verified, but do whatever you want...

Rekord81 wrote:

When I obtain a used instrument cluster (IC), does it need to be reset in the donor vehicle? Do used instrument clusters come with a code number for unlocking/pairing?

No. Try using the search function; it provides a good explanation of how to adapt another control module (external link to Ross-Tech).

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.

Rekord81 wrote:

I think that's it for the MSG. Yesterday, I measured the voltages (at the tantals) on the open MSG in the car. Everywhere, they were stable at 5V. The preheating indicator is NOT lit up, nor is the oil control lamp.

Did you have Ubatt connected to pins 23, 45, and 68 (which is the power supply switched by the 109)?
If so, an MSG defect does increase the likelihood of a problem, but instead of gradually worsening performance, it will almost certainly cause a sudden and complete failure in 99.9% of cases.

When the engine control unit (ECU) is connected to the car and the ignition is turned on, I measure 5V across the internal capacitors (on the open ECU), which is what it should be. If I then remove the relay from its socket, the voltage disappears.
On the lab table, I'm only supplying pin 23 with 12V, but internally, pins 23, 45, and 68 are connected. When measuring at the K-line to the WFS (pin 61), I see around 12V, but no data is being transmitted. I've tried using 10k pull-up/down resistors both against 12V and against GND, but still no data output when power is turned on. Does anyone know which IC in the MSG drives the K-line?

The car didn't gradually become worse; instead, it started failing to start more and more often, or would stall immediately after starting. When driving normally, everything seemed fine, and it would continue running.

Andi.

Rekord81 wrote:

When the MSG (Motor Steuergerät - Engine Control Unit) is connected to the car and the ignition is turned on, I measure 5V on the internal capacitors (on the open MSG), which is what it should be. If I then remove the relay from its socket, the voltage disappears.

This indicates that the 109 is intact, at least during the measurement. But as an electronics technician, shouldn't you be able to easily check for cold solder joints?
Are all the grounding points in good condition from a vehicle perspective (points 1, 24, 46, and 33 = sensor ground)?

"All the solder joints are perfect, there are no parts showing signs of overheating, and visually there's nothing that indicates a defect. The vehicle is located in the workshop garage, so I can only access it when the workshop is open."
Connections 1, 24, 46, and 33 are internally connected to the MSG.

Rekord81 wrote:

The solder joints are all perfect, no parts show signs of overheating, and visually there's nothing that indicates a defect. The vehicle is located in the workshop inside the hall, so I can only access it when the workshop is open. The connections 1 / 24 / 46 and 33 are internally connected to the MSG.

Then, check the signals at the following pins (MSG in the vehicle, ignition on):

7/29/52 = HDK transmitter at the MSW: At least one pin should have a 10(?) kHz signal applied to it.

4/5/49 = MSW. After ignition is turned on, you should see some fluctuations between 0 and 12V, or PWM packets -> MSW self-test.

8/14/64 = NTC sensor (Diesel/Water/Charge Air): When the engine is cold, approximately 4V should be present for each sensor.

25/47 Magnetic valves for EGR and turbocharger boost control: these likely require a PWM signal with a duty cycle of approximately Ubatt.

68 = Diesel shut-off valve; likely around 12V during engine operation and when the starter motor is engaged (assuming everything is functioning correctly).

15 = Throttle position sensor, voltage varies from approximately 1 to 4 volts depending on the position.

guste100 wrote:

Zum Test kannst du das MSG an jedem TDI mit 90 oder 110 PS mindestens aus den Baujahren 94-97 testen. Der Motor muß zumindest für 1 Sekunde laufen.

Do you really have no one in your wider circle of acquaintances who has a suitable vehicle? Then you could briefly connect the MSG to it and would be certain within less than 10 minutes whether the MSG is actually defective.

Since the defect developed gradually, I agree with Ulf that a faulty MSG is unlikely to be the sole cause. Have you already reviewed the technical article on starting problems?

Hello,
um PWM usw. am MSG im Fahrzeug zu messen, müsste ich mein Oszi in die Werkstatt bringen. Dafür kann ich mich aber überhaupt nicht begeistern. Allenfalls werde ich dort mit einem Kristallohrhörer die einzelnen Pins auf dyn. SigPlease provide the text you would like me to translate from German to English. I need the text to be able to give you a translation.
Today, I'll be doing some more measurements at my desk. On Monday and Tuesday, I will focus on organizing a second vehicle for testing, or finding a tuner/MSG repair specialist in the area (KA) who can at least perform a basic "good/bad" test.

Will my Audi AFN MSG also fit into a VW AFN?
My MSG (engine control module) has the number 028 906 021 EM. Do all MSGs with the same last letters work, or does it also depend on whether the xxx EM-MSG comes from an Audi or a Volkswagen?

Andi.

Rekord81 wrote:

Will my Audi AFN MSG also fit into a VW AFN? My MSG (Modular Synthesis Gateway) has the number 028 906 021 EM. Do all MSGs with the same last letters fit, or does it also depend on whether the "xxx EM" MSG comes from an Audi or a Volkswagen?

No, that should be fine. At worst, the MSG in the VW might need a different coding to run perfectly - but even without WFS adjustment, the engine of a foreign vehicle will shut off after just 1 second anyway.

Am MSG tut sich überhaupt nichts, event. kommt der Prozessor gar nicht hoch, oder im ROM/EPROM sind einige Bits gekippt und die Checksummen stimmen nicht mehr (könnte ich mir vorstellen). EOkay, go ahead.

On xbay, there are many control units with the same number but different letters at the end. I assume they are not compatible?
PS: I just found out from a tuner that GL, JD, and JC might also be compatible.
PPS: Another (scrap car dealer) says that only EM is suitable.

Andi.

Search for "Bosch eCat" on Google, enter your part number, and see which other part numbers it has been replaced with. That way, you'll know which ones are compatible.

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.

Rekord81 wrote:

There is absolutely nothing happening with the MSG; possibly, the processor doesn't even boot up, or some bits have flipped in the ROM/EPROM, and the checksums are no longer correct (I could imagine that).

Statistically unusual, but given the expert knowledge based on records, the diagnosis is likely to be correct.

I'm curious, on the sidelines, about what internal processes could cause a Message Sequence Number (MSG) to initially fail rarely and then increasingly frequently – but still never crash during engine operation .

ulf wrote:

I'm curious, on the sidelines, about what internal processes could cause a Mass Air Sensor (MSG) to initially fail infrequently and then become more frequent in its failures - but still never completely seize up during engine operation

.
Speculative: Memory error (checksum) caused by a loose connection or electrically conductive debris.
between the memory legs.
The check is only performed during system startup. Risks to ongoing operations are... unpredictable!
The self-heating of the MSTG might be sufficient to reliably stabilize the system.
The bridges, or rather, the dirt loses moisture and becomes sufficiently resistive.

Best regards, Micha.

Hello,
I need your help again. I'm still looking for a replacement control unit for the Audi. There are some available with the Audi/VW part number, but they have different letters at the end.

Original part number (for Audi A4, manufactured in 9/96, with AFN engine, 110 HP, B5 type): Bosch 0281.001.553/554 -- 028 906 021 EM
If I understand ecat correctly, an xxx JD might also be a suitable option there.
I haven't found either of them on the internet.

What else can fit in there?
0 281 001 796 = 028 906 021 JC (ecat: Replaces: 0 281 001 553 = 028 906 021 EM, 0 281 001 655)
0 281 001 655 = 028 906 021 GL (ecat: Replaced by: 0 281 001 796 = 028 906 021 JC)
Is a previous version (here: GL) from the same successor (JC) still compatible?

Okay, here's the translation:

"So, in short:"
1) In the context of EM, it states: EM -> JD.
2) Regarding JD: -- (It doesn't specify what position JD is the successor to).
3) In the context of JC, we have: EM maps to JC, and GL maps to JC.
4) In the GL system, it is indicated that: GL corresponds to JC.

Does that also include GL and JC?

Andi.

Hello,

hat sich jetzt alles erledigt. Auto läuft wieder !

Ich habe gestern nochmal das MSG intensiv durchgemessen und bin letztendlich darauf gekommen, dass der Reset-Generator defekt ist, der im 5V Spannungsregler integriert ist. Der Reset war dauernd aktiv ! Die Reset-Leitung habe ich dann von der übrigen Schaltung abgetrennt und diese dann über einen separaten Reset-IC versorgt. Danach konnte ich auch die Bussignale, PWM usw. messen. Heute morgen dann ans Auto gesteckt, ist sofort angesprungen. VThe organ lamp was shining again.

Thank you to everyone who helped here.

Andi.

Rekord81 wrote:

Ich habe gestern nochmal das MSG intensiv durchgemessen und bin letztendlich darauf gekommen, dass der Reset-Generator defekt ist, der im 5V Spannungsregler integriert ist. Der Reset war dauernd aktiv ! Die Reset-Leitung habe ich dann von der übrigen Schaltung abgetrennt und diese dann über einen separaten Reset-IC versorgt. Danach konnte ich auch die Bussignale, PWM usw. messen. Heute morgen dann ans Auto gesteckt, ist sofort angesprungen. VThe halogen lamp was also working again.

Respect for the diagnosis and the repair.

Is that stabilization and reset IC a standard product, or is it a Bosch-specific part with some kind of proprietary encoding?