The trunk lid has 2 wire rubber harnest going from the car in each side - afaik (guess) the left side (drivers) is where the reverse cams data + some other black wires goes (posible power).
The right side have alle the nice colored wires.
I just did som wire testing using a induction meter 1 wire at a time (not exact)
I did not measure all wires,
but I got a clear signal on the Green/Brown wire when setting the car in reverse - this could indicate that a green/brown wire is used by the reverse light. other wires I mesured did not give a current indication - the white/blue did have some current while pressing the breake so posible this is the break light.
If someone is checking wires up front in the car, please messure a wire with green/brown color extra carefull.
this is the wire Im refering to:
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I guess Tesla might try follow some sort of a standard....
BS-AU7a 1983 Colour Code for Vehicle Wiring, from the British Standards Institution
acording to this green/brown is reverse light as well.