1983 brake light and turn signal issue

I have an 83 interceptor 750, my brake light does not work nor do my rear turn signals (front signals work,but I have to manually blink them), when i pulled the plastic over the tail, I noticed some sort of box, relay looking gizmo that said stop/tail on it, and also there are 2 other boxes that seem to go to the signals, the only light that works in the rear is the running light, all the bulbs are new, I have ran through the wires and they are all good, nothing broken, frayed or no unplugged dead end plugs, Im new to this old of a bike and Im stumped any help would be greatly appreciated

 

It's possible that the tail light senor box,the small one w/plug&3wires, is bad. I had a problem with mine this year as to not having a brake light. I bypassed the box to get it to work before I found another. The ONLY senor that will work is from a 83. The 84/85 is wired different. Not that it can't be change but you need a wiring diagram. I then had the same as you no running lights in the back (I rewired years ago). That turned out to be the contacts in my ignition switch wasn't aligning right. Fiddled with key and everything came back. I think I lost power to the brown wire or brn w/a stripe on it. The wiring diagram will tell you. I think there is only one power wire to the box. The turn signals are the three loose wires and have their own power. That's why they are working.

You can get an on line 83/85 FSM here: http://vfrworld.com/forums/1st-2nd-generation-1983-1989/31510-1st-2nd-gen-service-manual-download-links.html . Becareful when reading the wiring diagrams. There's one for 83 only then another for 84/85. They are a tad different.

I've seen several 83 tail light sensors on ebay when searching for mine about a month ago. Search for vf Interceptor. It will bring up everything for sale for those bikes 500-1000.