Searching for a switched power source in the boot!!!

[E39540V8]

Hello Everyone.

As the title suggests, I am trying to find a switched power source in the E39 boot. Due to parasitic draw issues I have removed the screen/nav system completely and am trying to install an android tablet/amp system.
As I understand it, the screen activated the amp in the original setup, I have tried using the power wire from this harness, linking it to the torch socket, through the harness into the back. I have also tried to run a separate cable from the lighter socket to the back, and I keep running into the same issue, I get static interference and noise when the indicators are used.

At first I thought it was a bad ground, so I grounded everything to the battery earth lead on the chassis in the boot, and also measured resistance with a multi meter, still no go.

I have done many searches and the other two options are a purple/white wire under the left hand tail light and another behind the fuse box, both don't have and voltage in my car.

Please not I do not have a head unit to activate my amps, I am after another way..


So I found the purple/white power wire that goes into the front nav screen,I had removed the fuses due to the draw and I get the static noise.

Any help would be great :)

E39540v8

[JaxPlanet]

I am not sure if I understand you correctly, but this may help:

The white wire going into the factory amp, which is in the boot/cargo area, is the remote turn on lead. If you have an aftermarket amplifier or other device that has a remote trigger wire, tap it into the white wire and it will turn on when the factory amp turns on. If amp/device you are installing does not have a remote turn on wire, then you need to install a relay. Then you can pull power directly from the battery and connect the relay's trigger wire to the white wire on the factory amp. You can study up on relays here: http://www.explainthatstuff.com/howrelayswork.html

I have pictures that may help in my "2003 BMW 525iT" gallery in my profile.

[JimLev]

He doesn't have the factory head unit so the white wire won't do anything.