Hi Rumcajs,
I’m currently having exact same problem. Bought a 2008 Nissan Patrol a few months back with a dodge remote and only one key. Purchased a new key with fob from locksmith they were able to program the chip to get both keys starting the car but have been unsuccessful in getting car into program mode to set up keyless entry.
Also put car into Nissan dealership who were also unable to program the keyless entry.
At a loss as I have $200 key now that starts the car but does nothing else.
Im far from mechanically minded but judging from your diagrams above I just need to go through and test all the wires/connections with a multi meter and find circuit M133?
The beeping happens when the key is in ignition with door open so I was also wondering if you could supple further details on how to hack the multi remote signals. Central locking also works fine.
Cheers,