Rear defroster doesn't work on 2000 Accord?

Question

The button on the dash lights up, but the rear window doesn't defrost at all. What's the likely cause?

Answer 1

either the relay or the defroster line itself.
Check the voltage at the terminals at the rear window. If there is current, then check the lines at the window. if they are scratched/broken, then you found the cause.
If there is no current at the terminals, check the relay at the fuse box, (I imagine you already checked the fuse).
Those are the most common causes.

If that does not work, you will need to troubleshoot by tracing the current.