Note the brown/red is the DFAHL signal, which is the wheel pulse signal from the rear left wheel. You can tap into this signal on the ABS/DSC control unit if you want. On anywhere else where you see the same wire colour. Brown/red is always, and only, the DFAHL signal.

The reason you don't see time and date and the nav cannot work is because it is not getting the correct data over the ibus from the instrument cluster. The first thing the nav does when it starts up is ask the instrument cluster for time and data and vehicle/country settings. If the cluster doesn't respond, it won't work.

So firstly check the ibus connection exists - can you control the radio volume from the steering wheel? If so, the ibus connection from vehicle to nav system exists.

If your nav still doesn't operate, it is because the data is missing, because you have the Low instrument cluster