I added a set of spot lights to the front of my '04 tonight and since my factory fog light wiring is in use (my 03 S was prewired for fogs but did not have them so I used that wiring) I needed another power source. Granted this way is not as easy as just adding an external relay somewhere and grabbing power from the battery, but I am a stickler for wiring and electronics, so if I can make something function and look factory, Im all about it.

My truck did not have SLS, so the R5 relay terminal was empty in the under hood fuse box. There is a 30A fuse on that relay power feed, so that should be more than enough for most lights or other accessories.
You will need to un-bolt the fuse box to access the underside. (3 8mm bolts) and disconnect the battery and alternator feed wires (10mm bolts)

Heres the two plugs you will be "intercepting". The white/black is the power out to your accessory.


I cut the white/black wire and sealed off the cut end that is still in the car. I took the end with the plug and added my two new spot light power wires.


The gray plug underneath that is where you will be hooking up your +12v relay trigger. There is a brown/purple wire, second pin in from the right, bottom row. You are going to cut this wire and add your trigger wire to the plug side. Seal off the cut wire on the vehicle side.


I have my relay +12v trigger hooked up to a latching rover switch (cruise) getting power from the parking lights under the dash (red wire in the harness running up the steering column)
Clean and easy!

 

That's a good idea

If anyone needs them, I can supply new terminals to fit both of those connectors

Another option would be to intercept both of these wires away from the fuse box.

The Brown/Purple wire can be intercepted at its other end, at C0655-6 at the SLABS ECU, behind the glove box.

The White/Black wire runs only a short distance from the fuse box to the main harness to chassis harness connector junction - C0376/C0390

On vehicles without SLS, one of the terminal cavities in C0390 will be empty, as there will be no White/Black wire in the chassis harness for the SLS compressor.

C0376/C0390 are BMW 2-way sealed 2.5mm pin and socket connectors.

Terminals and wire seals to fit these connectors can be bought from your friendly local BMW dealer.

I have the BMW part numbers, if anyone's interested?

Or, if you don't fancy being spotted in or around a BMW dealership, I can supply terminals and wire seals to fit the connectors

.

 

Ahh that would have been even better to get the trigger at the SLABS inside the car.
Good info, Thanks!