M4500 - light sensor and backlight - General Hardware - Laptop - Dell Community

M4500 - light sensor and backlight


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M4500 - light sensor and backlight

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Hello all,

I am new owner of M4500. It is quite good machine bug has a few glitches. One of which is strange backlight control. This model is equipped with light sensor that can control backlight automatically. The problem is I cannot turn off the light sensor without loosing the ability to control backlight myself.


turn off light sensor (fn+left) -> fn+up/down does nothing (I think this is the problem)

turn on light sensor (fn+left) -> fn+up/down works but light sensor too (you cannot control backlight precisely because it keeps changing)


I think it is some kind of bios issue. Could someone with M4500 confirm this?


Thank you

All Replies
  • Dell has changed the function keys on some new laptops. Try the F1 to F12 keys without using the FN key. The F4 & F5 keys might have a brightness control as my new 1764 does. Check them out for symbols. The top symbol doesn't require the FN key, but the bottom one does.  This fn key/no fn key setting can be reversed in the bios. Refer to your manual to see if this applies to your model.

    Edit-- I just checked your model and this doesn't really apply to your computer, but it might help some other new laptop owner.

  • Thank you but I am sure fn+up/down are the correct keys, they even work when light sensor is active