1) Turn the amp on and volume up a little
2) Plug the cord into the amp, but unplug it from the guitar
3) Touch and release in succession around the metal end of the cord - you should hear a deep hum start and stop.
If you do NOT hear the hum start and stop, it's your cord or amp (you ruled out cord)
If you DO hear the hum start and stop, the problem is your guitar. If so:
4) Buy my guitar: http://seattle.craigslist.org/see/msg/264735111.html