Hi people. Sorry if this has been asked before but my tiny mind is being blown by this. My OS headlight dipped beam failed. No problem I think. I’ll just change the bulb. So one new bulb later, nothing. Another bulb…still the same. So out comes the multimeter. No bulb in, 12v on both dipped & main. Ok…try another bulb…3rd time lucky I thought. Nope. Check the voltage with the bulb in…nothing. Bulb out…12v. Connections all clean, used some contact cleaner, still nothing. I’m at a loss….

Just because your multimeter (very high resistance, probably megohms) indicates 12V, does not mean that you can draw 5A (low resistance bulb) from it !  

I would look at your relays and fuses.  The decal on the back of the glove box will tell you which relays and Fuses they are.  Swap the relays over. and see what happens.  Unfortunately the circuit diagram uses different nomenclature from the decal, and also has the modifications for my 2007 Zetec S