Am I able to use the scanning part of printer when

Hello,
It is a very interesting question. I often wondered if my Brother MFC-5460CN would scan even if there is no ink in a cartridge. I guess it your lucky day, because yesterday I changed the cartridges, and your question gave me the opportunity to find the answer.
I replaced one new cartridge with a depleted one. As expected my printer refused to print but did not balk when I scanned a document.

At least my printer scans if there is no ink.
To verify if your does too, wait until a cartridge is depleted and try to use the scanner, and you will have a FIRST Hand answer.

Hope it helps.