Audi A6 2.5 TDI: No Diesel - Troubleshooting

Hello, I replaced the timing belt on my sister's Audi A6 with the 2.5 V6 AKN engine.
When I tried to prime the fuel lines by turning the ignition, I didn't hear the fuel pump running. I checked the circuit all the way to the engine control unit and found that the engine control unit wasn't providing a ground connection on pin 10 of connector 4.

I disconnected the wire from the engine control unit and manually provided a ground connection to the wire leading to the fuel pump relay, and sure enough, the pump started running. I disconnected the fuel line on the engine side at the filter, but still, no fuel is reaching.

Unfortunately, I'm at a loss. During the belt replacement, I disconnected the battery's ground cable. Now, when I reconnected it, the engine control unit and fuel pump seem to have failed?

I'm looking forward to hearing your ideas.
Thank you in advance.

At AKN, this is not a pre-feed pump; it's a pump that only fills a suction chamber in the tank. It only starts operating when a certain tank level is reached.

Therefore, depending on your fuel level, everything is normal for you.

...in other words, you need to "manually" bleed the system using a vacuum pump and a lot of patience. You can find the explanation using the search function. Bleeding instructions for AFB, AKN, and the simple V6 TDI engines.