Quick question. The H7 dipped beam bulb has two wires going to it, a black one and a brown one. Can someone with a wiring diagram have a quick look and tell me which is positive and which is negative please?

I have a feeling the black is positive but just need to make sure.

Thanks.

Multimeter?

 

I believe you're correct and brown is ground, black is power. This also suggests that's correct: http://www.briskoda.net/forums/topic/338193-london-colour-hid-upgrade-kit-install-guide/

Perfect. Thanks.