Q: My headlight bulb on 2008 mini cooper dont turn on even after replacing a new one and the fuse are all ok,what can be the problem?

Using a voltmeter, check for battery voltage at the bulb socket with the headlight switch on (be careful not to short circuit the bulb terminals). If you detect battery voltage at the bulb socket, that means the the bulb holder is probably not making good contact with the bulb base and will need to be repaired. On the other hand, if you do not detect battery voltage at the bulb socket, the bulb circuit has to be traced back to the power source to find the interruption in power. Typically, the circuit trace is performed using the factory service manual wiring diagram because all the visible wiring that needs to be checked is color coded. To resolve this, if you need the assistance of a Mechanic, dispatched by YourMechanic right to your location, please request an electrical component diagnostic and the responding certified mechanic will find and fix the cause of the fault. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.