LMM Pinout: Hitachi for Audi A4 B6 2.5 TDI

Hello everyone,

I recently purchased the Audi A4 mentioned above. Unfortunately, it's running very poorly.

Error message: LMM short circuit to ground.

It uses a linear motor module (LMM) manufactured by Hitachi.

I tried measuring the voltage at the connector for the mass airflow sensor (MAF) using a multimeter, but apparently, there is no board voltage of 12 volts reaching it.

Where can I find the pinout diagram so that I can measure correctly and accurately?

The engine is hard to start, it runs roughly when idling, and when I accelerate, it feels like it's only running on five cylinders. The check engine light is on.

It doesn't matter whether the mass airflow sensor is connected or disconnected.

Best regards.

Hi there,
Since the engine control light is already on, there are definitely error codes stored. You won't be able to proceed without a diagnosis. Please run an auto scan and post the results here.
hg
Herbert.

Hello,

I would be happy to do that. Fortunately, I have already purchased and installed VCDS on my laptop.

I won't be able to make it today because the Audi is currently stored in a rented garage.

As far as I can tell, the only error detected was a short circuit to ground at the mass airflow sensor (MAF).

The scan will likely provide more information; I'll post it here.

By the way, I can't measure any voltage at the connector to the mass airflow sensor (MAF) when the ignition is on. Is there a broken wire? Is there a fuse that supplies power to the MAF sensor?

Best regards.
Holger.

Okay, I'm ready. Please provide the German text you want me to translate into English. Just paste it here, and I will give you the translation.

Great, thank you for that!

"There is no voltage at pin 2 on my device, and that's where the problem starts."
I guess I'll have to trace the cable and see what's going on.

I'll still do the full scan and post it later.

Thank you very much.
Holger.

Is there anyone who might have experience with why there is no voltage on pin 2 of the LMM (Mass Air Flow sensor)?

Is it a fuse or a relay that's causing the problem?

Regards,
Holger.

With more precise information and an automated scan, we could have provided much more targeted assistance. As it is, we have to rely on a lot of guesswork.

Ich habe nun mal für einen A4 BJ 2002 mit Motorkennbuchstaben AKE geschaut. Dort bekommt der Luftmassenmesser sein +12V an Pin 2 von einer Plusverbindung aus dem "Leitungsstrang Motorraum". Daran hängen auch Teile vom Automatikgetriebe (falls verbaut) sowie der Schalter für die Rückfahrleuchten (falls Schaltgetriebe). Daher mal prüfen, ob das Rückfahrlicht noch funktioniert. Versorgt wird das Ganze aus dem Leitungsstrang "Schalttafel". Dieser wiederum bekommt die Spannung von Sicherung 231 (15A). (oberste Reihe der großen Sicherungen. Mitt(for secure storage).

Now the only question is whether this information applies to your specific model year and engine code.

Best regards (from someone who drives past Schleswig every day).
Sure.

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

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

Good morning, Guste!

Thank you for the information.

Mine has the engine code BDG with a manual transmission.

"Sorry, I'll still run the scan with VCDS later; the Audi is currently in a rented garage."

Thank you for the tips; I will inspect the vehicle as soon as I have access to it.


You're very welcome and best regards.
Holger.

Audischeuche wrote:

Mine has the engine code BDG with a manual transmission.

Okay. The information I provided also applies to a 2003 BDG model.

Yes, great!

I'm going to drive to the hall this weekend and take a look.

You're very welcome!

Regards,
Holger.

Okay...

I was at the vehicle and performed a scan.
Now I just need to figure out how to set this up on my laptop.

The tip about the fuse worked once; it was a 15 amp fuse.
(in my case, it's number 34) that burned out in the motor controller.

I replaced them and then cleared the stored error codes with VCDS.

The check engine light is off, and there is battery voltage present at pin 2 of the mass airflow sensor (MAF).

So far so good, but unfortunately the engine is still running like it only has 5 cylinders; it responds to acceleration but shakes slightly. It sounds like it's only firing on 5 cylinders. However, diesel fuel is being delivered to each injector.

What's noticeable is that when I disconnect the connector from the needle lifter, I don't observe any change in the engine's running.

I'm trying to adjust the scan; it's a recording I made when I replaced the fuse.


Thank you for your help.
Regards,
Holger.

I'm sorry, I can't seem to adjust the scan settings here.

I will upload them as images.

Image 2 from the scan.

And one more thing...

That should be it.

Just a note: the "Navi Plus" system is no longer installed in the vehicle, which is why you're seeing those error messages.

Regards,
Holger.

Audischeuche wrote:

Sorry, I'm not able to get the scan set up here. I will upload them as images...

Hello,
Here's a small note regarding the settings:

Click the "Select File" button, choose the desired file, and then click the "Upload Selected File" button...
The Autoscan is a simple text file, so if necessary, you can use copy & paste .

In emergency mode, pre-defined parameters are used, but the engine still doesn't run like a "piece of junk"!
Is the engine mechanically sound?
Was the compression checked / was a leak test performed?

Audischeuche wrote:

So far so good, but unfortunately the engine is still running like it only has 5 cylinders; it responds to acceleration but shakes slightly. It sounds like it's only running on 5 cylinders. However, diesel fuel is being injected at each injector.

You can carefully loosen the pressure lines at the fuel injectors one by one while the engine is idling (place a cloth around the fitting to prevent fuel from spraying all over the engine compartment!).
to determine which cylinder is not functioning properly.

The question is also why the fuse for the motor control burned out? Is anything else connected to fuse number 34?

Best regards, Richard.