This depends on the model. Hold the Fn key and look for a lightbulb or a sun with an up arrow in the same color as the Fn key.
Your screen goes dim because all the energy from the battery in the charger goes into you're laptop so when you unplug it. It goes dim but there is ways you can fix it that how my laptop works.
Alternator
Twist the headlight switch.
Take a closer look at the LCD screen. Can you see a very dim image on the screen? If you can, most likely there is a problem with the inverter board. The inverter board is a power supply for the LCD screen and when it goes bad the screen looses backlight. The inverter board is located inside the laptop display. In order to replace it you'll have to open up the display panel.
You can brighten dim LED lights in your room by checking the power source, ensuring the bulbs are compatible with the fixtures, and cleaning the bulbs and fixtures. Additionally, you can try using a dimmer switch or replacing the bulbs with higher wattage ones.
Keyboard symbols, such as ! " £ $ % & @ { } are self explanatory. On a laptop (usually) there may be other symbols to be used along with the Ctrl, Alt, and or a special function key (fn) to brighten or dim the screen, to raise or lower the volume, and so on.
The outlook seems rather dim. Let's brighten our outlook with optimistic thoughts.
If you know where to change the odometer/tripmeter display... Instead of pushing that control, turn it counter-/clockwise to dim/brighten the dash lights.
I had problem similar to this. If it's not lit at all, the problem may be in your lighting of the screen. If it is just very dim, the light sensor is malfunctioning. Also, it will dim if your running or headlights are on.
Illumination is the ability to lighten the screen or darken the screen with the other dash lights on the vehicle. normally you will have two orange wires coming from the cars wiring harness one with a white stripe one without. The orange/white wire will make the stereo dim or brighten with the dash lights. the solid orange wire will dim/brighten the stereo with the headlights. so if it is night you will have the headlights on, when you turn the headlights on the stereo dims so the light from the stereo will not blind you at night. while the headlights are off the stereo will be bright so the stereo light will be visible in the daytime
Press down the Fn key (near the ctrl key) tthen press F5 a small window will pop up now use arrow keys to increase or decrease brightness. regards Sivanand
On my zx2 there is a button on the lower part of the dash by the drivers door that you can brighten or dim the lights... Not sure this is your problem but it is worth a try ... I use it to dim them when driving at night..