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Asus N71JQ enable backlit keyboard.
Hey guys!

I am using a asus N71JQ (came out ~2010) which do not came with backlit keyboard.

I found that some very similar laptops (asus G73JH and G60) have exactly the same keyboard but with backlit. Those keyboards have an additional FPC for the LED. I also found on a forum a guy who installed such backlit keyboard, but he made an external circuit to power the LED with a button that he added on the side of his laptop.

But I wanted to do something more clean. I would like to be able to use Fn+F3/Fn+F4 to increase decrease the brightness as you would on G73JH.

So I started to look for N71JQ and G73JH schematics, which unfortunatelly cannot be found anywhere on the web. However I could find N61J schematic. On this schematic I found out that the keyboard backlit is controller with a PWM from the IT8570E embedded controller (EC):
This PWM goes to a mosfet the mosfet enable/disable the connection of the FPC to ground (5V pin is always connected). By changing the PWM the CPU can vary the brightness of LED.

Then I checked my motherboard (N71JA rev2.1) of which I don't have the schematic. However I found that it has same EC IT8570E. Also to my surprise I found that there is a FPC connector available for the LED backlight! I checked and there is same mosfet as on the schematic I saw. I also checked and the mosfet is connected to the pin 32 for IT8570E which is PWM6 (same as on N61J schematic).

I also checked that the 5V is correctly applied to the FPC.

So all the hardware is already ready to support the backlit keyboard! (Which is strange as no asus N71 serie never had backlit. And the motherboard is not used on other models. So they actually paid for components that never ever have been used.)

So I connected my new keyboard, the keyboard works, previous shortcut I had also worked (Fn+F5/Fn+F6 increase/decrease luminosity of LCD for example) but Fn-F3/F4 does nothing still.

There are several drivers related to keyboard shortcut (see this forum)

Quote:- ATKDrv Utility: This is required because it is actually the ACPI driver. This is what tells your OS about the power state of your system and allows for power settings to be changed by the OS. It is also responsible for pulling battery information from the BIOS.
- ATK Generic Function Utility: This is required as it allows for communication between the ACPI and all the shortcut keys.
- ATK_Hotkey Utility: This is required to make use of all the function key shortcuts.

I checked on asus website for drivers, and found the first 2 are exactly the same between N71JQ and G73JH. The third the version is different so I tried uninstall it, then install the G60J version, Fn-F5/F6 still work OK, but Fn-F3/F4 still nothing happening. (I just realized I have not tested G73JH, but this don't have exactly the same drivers than NJ71JQ and G60, will feedback when I had a chance to try).

Then I found this topic about backlit keyboard issue happening after bios update on G73JH..! So that brought me to understand that the problem might be in the Bios!

I have thought about 2 possibilities : 
- Try this kbfix even if the asus model is different. Some people reported that it worked on their model. But it sounds very risky? (On the page 4 of this forum someone explain what the fix actually do.)
- Flash the Asus G73JH bios on my N71JQ : this somehow sounds like a terrible idea...
- Analyze the two bios (G73JH and N71JQ) and try to find the difference. But I have virtually no idea how to proceed... Maybe trying with a binary explorer like PEBrowserPro?

Any hint would be awesome!
I tested the kb fix without success. it returned 0, which i don't know what it means! something suggest that the value the program is correcting is already corrected (something unclear saying 7C appears)

I tried install the atk package for the g73jh, now fn+f3/f4 show the icon of keyboard light but it does not work still.

I think something is missing in the bios. My idea would be to get the EC part of the g73jh bios, try to find which function write on PWM6 register and try to copy that to the N71JQ. If the code was readable it would be easy task but as it is ...

Another idea I have is to write a small program/driver to do just that, read and write directly in the EC register to turn on off the led. However I am not sure how to read write on the EC register with a compiled langage as C.
I know there's a program call RWEverything which enable to write in the EC register, but it's not permanent.

Also I tested RWEverything and it crashes my computer at launch. I tried all the version, the same happens. As soon as the .exe is launched I have a BSOD

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