The following is information on wires that can be used to hard wire a radar detector to come on with the igniition key in your E39 (tested on a 1998 540i Sport). Please post it for others to use if you feel that it is worthy.
I did not like the detector cord going from my cigarette lighter up to my windshield, and that the cigarette lighter always has power running to it (ignition on or off). So I wired up my Passport 8500 to an unused set of wires up by the courtesy lights & sunroof switch. I only regret that I did not have my digital camera with me to take pictures, but this pretty easy stuff, I've done it on every car that I've had before.
- Remove the courtesy lights. I pryed with a screwdriver until I could get my fingers a place to grip, then they just pop down. Disconnect the rectangular 6 pin connector and place aside.
- Remove the sunroof panel. The whole panel slides slightly towards the front of the car, then pops down. Dissconnect the flat 6 pin (5 used) connector and place aside. Note, there may be an additional connector if you have the BMW phone option.
- There is one rib between where the courtesy lights and the sunroof panel came together. On the driver's side near this rib you will find two (2) flat three (3) pin connectors. One has an all black connector with Yellow/Black/Clear wires, you don't want this one. The one that you want is a black connector with a white cap, and has Green/Grey/Brown wires.
- The wires that you want are the Light Green with a White Stripe, this is the positive (+) that comes on with when the ignition key is turned. The Brown wire with no stripe is the ground (-).
- Slide the white cap off of the connector and use a pin to depress the tab that holds the electrical pins in the connector and slide them out of the connector.
- Run the wire for your detector through the wire hole for the rearview mirror to the 2 vehicle wires. Make sure that the wires are run high and off to the side in this opening, and make sure that everything is above the rib.
- Twist the positive (+) wire from the detector to the vehicle positive (+). Do the same with e negatives (-). Plug in the detector and turn the ignition key forward, and it should work.
- Solder the positive (+) wires together and tape, same with the ground (-) wires.
- Tuck any excess wire up and off to the side and reassemble.
- You are done.
There might be an improvement to this if someone wanted to find the "Male" 3-pin connector that is the opposite of the connecter in the car so that no factory wiring needs to be violated. __________________ Thanks,