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Released October 24, 2011 / 2.2, 2.4, or 2.5 GHz Quad-core Intel Core i7 Processor

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Keyboard Backlight Doesn't work

Hey,

So I last week I turned 18 and got my stepdads Macbook pro 15 late 2011. He never really used it so its in great condition except the battery life.

Anyway I noticed that the backlight doesn't work sadly. I tried resetting SMC and NVRAM with no luck at all. I tried Full hardware test and no problems found and aswell I tried the setting low light feature under settings with no luck either.

The weirdst part is that in a 100% dark room you can see the keys are lighting up very very poor and then sometimes when I'm restarting my pc it blinks for a second on full power I think.

So now my question is "where is the Keyboard Backlight cable located?" I already opened up the pc and been unplugging a few cables and plugging them in again since I saw some other guides online for older or earlier models but no luck.

Later today I'm planning to switch out the old HDD with a new 500 GB ssd so maybe a new start over will fix it but I don't think it will.

Thank you in advanced.

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The cable for the keyboard backlight is located next to the central fan in the 15" models. It is a small 2 pin cable that comes up between the logic and the fan. (its known as the right fan, but is located in the centre of the machine)

If its coming on occasionally, then its not likely a connection problem. its either the LEDs failing, or an alignment problem. its typical for older machines to get a lot of dust and dirt between the layers, which warps the plastic diffuser sheet. if that is not perfectly flat, the LEDs cannot distribute the light effectively, so it will appear brighter in the centre than on the outer edges.

The other thing to think about, is on these models, the OS is what alters the backlight of the keyboards. on earlier OS versions it will come on under different circumstances to later OS version. So knowing the OS that you are running will help trace this fault, but if you cover the isight camera in the display with your finger, then adjust the keyboard brightness with the F5 and F6 keys, it should come up.

On later OS versions, if the camera (it has an ambient light sensor built in) recognises a light environment and you press the brightness keys, it will show a no access sign on the screen until its in a dark room or you cover the camera.

I hope this helps.

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Hey Jon,

I found the cable I think but not sure. Earlier today before making this thread I already tried unplugging it and plugging it back in again several times with no luck.

I cleaned it today aswell since it had a dust in the air vents.

I just flashed El captain on a 100% new SSD and that didn't fix it either.

If I cover up the camera and the sensor very close to the camera only the screen dims of what I know.

I hope we can figure something else out.

I appreciate your help!

por

Did you attempt to press the keyboard brightness keys while covering up the camera? as the keyboard backlight will come onto the last preset brightness setting used, so if it was off last time, when you cover the camera it will only dim the LCD. But if it is on, both the LCD and the keyboard should adjust at the same time.

It is entirely possible that the LEDs are faulty, or there is some damage to the logic board.

If you are really savvy, and very carful, you can test the backlight sheets separate to the logic board.

They require 18v to turn on full brightness. We typically use 2x 9v batteries in situ with a small bit of wire, then hold it on the keyboard backlights cable (making sure to get positive and negative correct, and making sure the logic is unplugged from mains and battery while working on it. we usually remove the backlight sheet from the machine during this test, but it can be done in the machine as well)

You may have a logic fault. Did you get any backlight at all, or none ever?

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