BMW E90 fog lights rear and front

Detailed instructions for replacement of bulbs in the front fog lights of a certain car model are contained in its technical documentation. The procedure largely depends on the engine bay layout. Sometimes it’s more convenient to perform this job from the bottom of the car, sometimes from the top.

Before starting the replacement, disconnect the negative battery terminal. After this, gain access to the light bulb holder. If you’re going to work from the bottom, put your car on a service pit or raise it on a lift. It’s better to remove the wheel. Next, unscrew the fasteners of the wheel arch cover and pull it aside. In some cases it’s easier to reach the bulb holder from the bonnet side. To this end, unscrew the fasteners of the headlight and remove it.

After this, turn the bulb holder counterclockwise to remove it from the fog light housing. Remove the blown bulb and install a new one to its place. When doing this, do not touch the glass envelope of the bulb with bare hands.

You can start the replacement on your own if you have basic electrical skills. You will need terminals, connectors, a 4-pin relay, a 15 A rated fuse, wires, and a fog light switch. You can buy all these items as a kit. Also, prepare pliers, an electrical tape or heat-shrink tubing, a knife for stripping wires, and crimping pliers.

Usually, fog lights are supplied with an installation manual where you can find the connection diagram. Typically, the procedure involves the following steps:

1. Remove the dashboard or/and centre console.
2. Pull out the dummy button and insert the fog light switch into the socket.
3. Install the lights into their mounting seats in the bumper and attach their connectors to them.
4. Ground the negative wires from the fog light connectors to the chassis. Connect the positive wires to the corresponding relay contact.
5. Connect another positive contact of the relay through a fuse to the positive battery terminal, and the negative one – directly to the negative battery terminal or to the chassis. The fourth wire should be pulled into the passenger compartment and connected to the button. Connect the second contact of the button to the positive contact of the marker lights.

Car manufacturers don’t equip vehicles with HIDs. Moreover, this kind of tuning is illegal in most European countries, because:

1. Reflectors of the standard factory-equipped lights are not designed for operation with gas-discharge lamps. This results in incorrect light beam formation, which increases the risk of dazzling oncoming drivers and can cause a road accident.
2. Dirt on the surface of the lens considerably distorts the light emitted by a HID lamp. In case of headlights, a headlight washer can solve the problem, however, fog lights aren’t provided with it.