hi all having problems with the rear demister in my 96 sti wagon.. light on the button doesnt come on at all?? and demister does nothin to the rear screen at all?? checked all fuses under dash they seem to be ok..

 

Light on the button may just be the bulb gone.

First job is to use a multimeter, or simple circuit tester to show if the screen is getting power at the rear, and if it has an earth.

Once you have checked there, if the answer is yes, the screen needs replaced, if the answer is no, move to the switch and check for power in/out.

DON'T rely on LOOKING at fuses, I've seen blade fuses that look fine and are dead, check with a multimeter.

Finally, look to the relay.