First step of any electrical troubleshooting: What is your voltage with the engine running?

If it's less than 13V then your fusible link might have blown.

 

Suspect that you don't have 12 volts at the big wire going to the alternator.
Mountain Man is correct, blown fuse in this wire. About a foot from the positive battery terminal is a black bulb on the wire, this is where the fusible link is located

 

also check your voltage at the back of the alternator