That wiring was designed for the now unavailable (for good reason) factory phone. It’s useless now.
If you want Bluetooth you have 2 options:
- buy an adapter kit that uses the factory wiring for the trunk mounted cd changer (2 cables: power and audio+control),
- buy an adapter kit that plugs into the main connector at the back of the head unit.
Both solutions use the cd changer interface with the head unit. The first solution is a bit of a PITA as you have to run a cable from the trunk to the console. That means running the cable under the carpet in the passenger cabin. The second solution is easier.
Be advised that BMW changed head unit suppliers for E46 model year 2003.
The 2003 and later head units are made by Alpine. These units have an extra connector at the rear for the auxiliary function. So, you could swap out the head unit with a later model. Check eBay. This requires a cable adapter and some other stuff. Search this forum for a thread on this option.
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