Audi engine control unit (ECU) AAT - engine

Hello everyone!!!!! I'm having the following problem: Audi C4, year 1993, 2.5 TDI, AAT engine.
He has an engine control unit with the number 4A0 907 401. Unfortunately, this control unit does not have the GRA function implemented. My Audi dealer told me that for this model year, there are control units with and without GRA. However, since I want to have GRA, I obtained a different control unit. The number is the same, but it has an "E" at the end. Unfortunately, the car does not start with this control unit. I suspect that this control unit has an immobilizer. (Mine doesn't have anything that advanced). Is there a way to permanently disable the immobilizer? Or do you know anyone who might have a control unit with GRA lying around? Or is there any other way to get a working GRA? I've now been driven by ambition, as the friendly dealer said: "If it wasn't included from the beginning, you'll NEVER be able to get it working." Oh, and: When trying to unlock the function in the control unit, the message "unknown function" appears.

I'm really curious to see if a professional can help me show this dealer how good "diesel mechanics" are!

Hi.

'That will never work. You have a first-generation AAT (Engine Control Unit). The ECU (Engine Control Unit) you have in your hands belongs to a third-generation AAT. This one has a different ESP (Electronic Stability Program) and, as you suspected, an immobilizer.' To my knowledge, the GRA (presumably referring to a specific feature or functionality) only applies to the AATs (presumably referring to a specific type of document or software) of version 3.

Yes, yes, those 'friendly' people seem to have some knowledge gaps when it comes to this old AAT (presumably referring to a specific system or technology). Unfortunately, I've had to experience that myself.

Do you have any suggestions on how I could obtain a GRA (General Release Authorization)?

Right off the bat, I can't think of anything. Since the engine has electronic throttle control, you can't do anything with a conventional controller. I'm not sure if there are any control units that have that function integrated. I have a version 3 AAT, and it wasn't a problem with that.

"That's exactly the problem: Some ECUs have the function, others don't, but they all have the same part number! A friend of mine once installed an ECU, and everything worked perfectly (of course, he's not willing to give it up). I don't want to spend a lot of money buying ECUs just to find the right one eventually." Thank you for your answers!

Please write down everything that is on your STG (Steuergerät - control unit) and what is on the STG of your friend.
I have, for example, two STG files here:
Bosch Part Number: 0 281 001 128
Audi Part Number: 4A0 907 401
Software version: D24 (this is indicated on the small, white sticker).
For the 401 model, there are also the data versions D35, D47, and D49 available.

Best regards,
Rudi

I have the engine control unit (ECU) here with the following part numbers: Bosch number: 0 281 001 128, Audi number: 4A0 907 401.
The white sticker says:


D49T
*364.28* 078
*28RT8934*
*6923.00107*




Unfortunately, that's all the information I have. I can't get any more data from my friend because he has moved, and the car was also sold in the meantime. I've been dealing with the GRA issue for a few months now .

Best regards from me.