Replacing my laptop keyboard with backlit keyboard

Hi,

If your original keyboard is not backlit, you cannot replace it with a backlit one. This is because the backlit keyboards have an extra ribbon cable at the back which plugs into the motherboard and power the backlight. If your original keyboard is not backlit, then your motherboard does not have that extra slot for the second ribbon cable. You will be able to install the backlit keyboard on your laptop but the backlight will not work so it would be better to replace your keyboard with a non-backlit keyboard. 

Hope this helps

I have dell Inspiron 15 3505 can I replace my keyboard to backlit keyboard

The keyboard isn't separately replaceable -- you'd need to replace the entire palmrest-chassis assembly, to which the keyboard is permanently attached.  Beyond the cost, it requires totally tearing the system apart (service manual link below).  Given the potential for damaging something not covered by warranty, you will wind up with a voided system warranty.  Translation:  it's likely technically possible but practically it's not feasible.

https://www.dell.com/support/home/en-us/product-support/product/inspiron-15-3505-laptop/docs

@ejn63​ I will never ever ever purchase a Dell laptop again for this reason.  and over the last 25 years, I have had many. I feel like I have thrown $800 in the garbage. Cannot work in low light because you can't see the keys? And the backlit cable costs about $1. Good move Dell, you lost a lifetime sale of an entire family to have saved $1 on the build! Give the head Engineer a raise!!