My 2000 Civic right turn signal blinks erratically--sometimes fast and sometimes slow. Both front and back lights come on. What is most likely the cause and how do I fix that?

 

When it blinks fast, that almost always means that one of the bulbs is not working. Check when it is blinking fast. When it blinks normal, both bulbs are coming on, so you won't learn anything by checking then.

 

Replace ALL the bulbs. Its old anyway. Done.