imac screen is black and not displaying anything.

My imac screen is completely black and i have not dropped or damaged the screen at all. I preformed a hardware test and this error code came up .

4SNS/1/C0000008: TL0p--124

Can anyone explain the meaning of this error code?

im using mac os x version 10.7.5

my model is IMAC 21.5 inch mid 2011