multipal electrical problems

2000 Continental blinkers, flashers, Interior lights, windows and trunk release have stooped working. I unhooked the battery and charged it then reattached the battery and tried it and after a few seconds they worked again. 2 weeks later same malfunctions. This time I can not get them to work. I have tried switching relays and have not located any blown fuses. Voltage seems good and steady. Any help would be appreciated.

Thirty years ago when I went to school for auto mechanics I had a wonderful electrics teacher who helped me to really understand a problem like yours. He wanted us to start with the obvious like switches and contact points, plugs, etc. But sometimes I would work on a real pain in the ass vehicle that mystified me, in that case I would start by hand feeling and wiggling the wires along the circuit, and see if there was a change in the problem.

Found several wires that had vibrated to the point that the insulation had worn away and grounded to the body, had to remove panels to do this, but with my 1975 Dodge truck, I managed to fix all the weird problems. I have only had one vehicle since (1984 Olds) that was an electrical head ache and used the wiggle wire method to find some well hidden problems. I would find out what lines are working on this circuit, spend some time hand inspecting the wires, do it in sections to isolate the area, and hopefully you will find a bad wire to attend to. I can relate to what you are going through, a real pain in the neck.