I am having basically the same problem with my 65 brake lights. have replaced brake light switch. when moving the turn signal switch down for a left turn indicator, my brake lights work just fine, when moving up for a right turn indicator, fuse blows, so with the information I have gleaned from this thread, I am going to guess that my turn signal switch is bad. Good ASSumption?

ted

 

Same problem only different, I moved your post to its own thread. I've found that sometimes the turn switch shorts to the turn signal lever.

 

I would not assume switch is bad without checking wiring first. Any recent work done that may have pinched a wire?