12 Volt Lead for Radar and after market NAV

[X3bummer]

Any tips on installing a power lead in the top dash compartment (where factory NAV would normally be installed). Ignition-switched would be ideal.

[BMW_tech]

i would go to radio shack and "create" a fuse block.in this block I would have power from the radio (B plus).From the block,I would have the 3 supply (B plus) wires leading to 1)back to radio/ 2) Radar detector/ 3) NAV unit.I would do the same for the 12 volt with key on.And with the ground,i would add a fourth wire that would actually lead to a body/chassis ground.