Audi A4 2.5 TDI: VP44 Pump Issues - Help!

Good evening, fellow diesel enthusiasts.

"I'm having a huge problem with my..."
Audi A4 2.5 TDI.
Year of construction: 2003.
Engine: AKE

It started with a faulty diesel pump control unit.

So, I ordered a used complete diesel pump online.
After that, I only replaced the control unit, and then I read out the error codes, which revealed three errors.

01318 - Control unit for fuel injection pump (J399)
03-00 - No signal.
01318 - Control unit for fuel injection pump (J399)
49-00 - No communication.
Bitte gib mir den deutschen Text, den du übersetzt haben möchtest.
ERROR WFS.


Since the immobilizer cannot be paired using the existing login code...
I've decided to bypass the immobilizer system.
The immobilizer is currently deactivated, and there is an error related to the immobilizer system.
It's also gone, but the startup still hasn't worked.


After that, I obtained another control unit.
And it's assembled.
The errors, specifically the two issues – one with no signal and the other with no communication – remain. However, I'm hearing that the quantity distributor is constantly...
It is being accessed/targeted/aimed at.
I still can't connect to the diesel pump.
I checked pins six and seven on the engine wiring harness. Both pins have a voltage of 12V once and ground the other time. When I disconnect the connector from the control unit, the humming stops.

I checked fuse 28 and there is only voltage when I try to start the motor, but it's not working. Also, I need to mention that the current engine control unit (ECU) is from an AKN engine, but only the ECU itself.
I would be very grateful if you could help me.

Unfortunately, I can't add "Auto Scan" because, for some reason, it doesn't seem to be working.
What I can say, and which I also find very mysterious, is that the fuel gauge isn't working, and I am 100% certain that the tank was completely full, and that I saw the gauge indicating "full" before the vehicle stopped starting.

UPDATE: ACCORDING TO VCDS, THERE IS NO VOLTAGE AT THE DIESEL PUMP.

Thank you very much for your help.