Anyone know where to tie-in a BEL 875 R remote radar detector power cord, so it will only be powered on when the key is on? Car is a 2003 745 Li. Have tried to find "key-on-only" power, but cannot find a full 12 volts. Power to brake light switch is in the right place, but voltage only shows 8 volts, and will not power the unit. Thanks for any help!