where is the fuse located for the rear defrost in 2000 dodge neon?

The owner's manual has a schematic of the fuses and identifies what system is controls. Defrosting puts out serious voltage to warm up the glass and I doubt that it can be realted to the dome light. Check the manual and find the right location for this fuse. Be sure to note the correct amp to replace it. Parts stores sell them. If the fuse is OK then you have a short somewhere in the circuit to include the control switch. A mechanic needs to resolve this .This system is important if you car is not sheltered when parked. Way too many people take chances by driving with ice/snow/frost on the rear windown during winter. Sorry about your troubles and good luck.