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

Rekord81 wrote:

The preheating indicator light is NOT illuminated, nor is the oil level warning light.

Was the relay 109 manually bypassed for testing? Or is your troubleshooting still focused solely on the MSG?

Rekord81 wrote:

I cannot detect any activity on the K-line while I am at home, on the lab table.

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

Rekord81 wrote:

I'm now assuming that the MSG is probably defective, and I lack the equipment (and, above all, the MSG wiring diagram) for further investigations.

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 MSG (Modular Scalable Gateway), does it need to be reset in the donor vehicle? Do used MSGs come with a code number for unlocking/pairing?

No. Try using the search function; it provides a good explanation of how to program a different MSG (external link to Ross-Tech).

Regards,
Guste.

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, I got stable 5V. The preheating indicator is NOT lit, 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 the car gradually deteriorating, it's more likely that it will suddenly stop working completely in 99.9% of cases.

When the MSG (module 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.
On the lab table, I'm only supplying pin 23 with 12V, but internally, pins 23, 45, and 68 are connected. I'm measuring around 12V on the K-line to the WFS (pin 61), but there's no data output. I've tried using 10k pull-up/down resistors both to 12V and to GND, but I still get no data output when I power it 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 it would stall immediately after starting. When driving, everything seemed normal, 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 the vehicle's perspective (points 1, 24, 46, and 33 = sensor grounding)?

"All the solder joints are perfect, there are no parts showing signs of overheating, and visually there's nothing that suggests a defect. The vehicle is in the workshop in the 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 in the workshop in 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 MSW: A 10(?) kHz signal should be present on at least one pin.

4/5/49 = MSW. After ignition is turned on, you should see some fluctuations between 0 and 12 V, 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: presumably, these should be controlled by PWM with a stroke of approximately the battery voltage (Ubatt).

68 = Diesel shut-off valve, likely around 12V during engine operation and when the engine is revving high (assuming everything is working correctly).

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

guste100 wrote:

For the test, you can test the MSG on any TDI engine with 90 or 110 horsepower, specifically models from the years 1994-1997.

The engine must run for at least 1 second.
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 you would definitely know 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.
Today, I'll be doing some more measurements here at my desk. On Monday and Tuesday, I'll focus on either 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 in 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 VW?

Andi.

Rekord81 wrote:

Will my Audi AFN MSG also fit in a VW AFN? My MSG (Engine Control Module) 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 VW?

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 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.

Bei xbay gibts eine Menge Steuergeräte mit der gleichen Nummer, aber mit unterschiedlichen Endbuchstaben. Ich nehme an, die passen nicht ?
PS: Hab gerade bei einem Tuner erfahren, dass GL, JD und JC auch passen könnte.
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 part numbers it has been replaced with. That way, you'll know which ones are compatible.

Gruß
Guste.

Rekord81 wrote:

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

Statistically unusual, but due to the extensive expertise available, the diagnosis is likely correct.

I'm curious, on the sidelines, about what internal processes could cause a Message Sequence Number (MSG) to initially fail rarely, but then become more frequent in its failures - while still never crashing during engine operation .

ulf wrote:

I'm curious, on the sidelines, about what internal processes could cause an MSG (Motor Sequential Gas) system to initially fail infrequently, but then become increasingly prone to failure - while still never completely seizing 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 bridge, or rather, the dirt, loses moisture and becomes sufficiently high-resistance.

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 model): Bosch 0281.001.553/554 -- 028 906 021 EM.
If I understand ecat correctly, an xxx JD might also be a suitable option.
However, 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) still compatible with the same successor (JC)?

Okay, here's the translation:

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

Does GL and JC also work?

Andi.

Hello,

Everything is resolved now. The car is running again!

Yesterday, I thoroughly re-examined the MSG (Main System Module) and ultimately determined that the reset generator, which is integrated into the 5V voltage regulator, is defective. The reset signal was constantly active! I then disconnected the reset line from the rest of the circuit and connected it to a separate reset IC. After that, I was able to measure the bus signals, PWM (Pulse Width Modulation), etc. This morning, I connected it to the car, and it started immediately. The preheating lamp also lit up again.

Thank you to everyone who helped.

Andi.

Rekord81 wrote:

Yesterday, I re-measured the MSG (Modular Sensor Group) in detail and ultimately concluded that the reset generator, which is integrated into the 5V voltage regulator, is defective. The reset was constantly active! I then disconnected the reset line from the rest of the circuit and powered it with a separate reset IC. After that, I was able to measure the bus signals, PWM, etc. This morning, I plugged it into the car, and it started immediately. The preheating lamp also lit up 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 a (typically) encrypted design?