No Power Upper Fuse Block

While driving to a Car Show last Sat., I noticed that my directional signal indicators in the instrument panel were not working. Upon further investigation at the show, I discovered that the brake lights as well as the actual directional lights were inoperative. Upon still later investigation (at home), I found the entire upper fuse block was dead; no backup lights, no radio, no signal/brake lights, no heater fan, etc. I removed the fuse block from the firewall and the yellow feed wire that provides the power to those fuses has no voltage. Does anyone know where that wire leads? It does not appear to be the same yellow wire that is at the junction block on the left fender in the engine compartment; at least there is no continuity between the two, which could be due to a broken wire or bad connection. Can anyone provide me with a recommendation on where to look next? I used to be user 59Bonvil but I had to change my name because I both changed my email account and forgot my old password. Thanks

Thank you for the wiring diagram. The color coding on the diagram is helpful but I don't know if it will be enough.  I tried putting 12V directly to the input connection and it still didn't work.  Thanks again for the diagram.

The wiring diagram is a great resource but a word of caution, the color on some wires change as they aged from 1959, they fade.  Lt blue looks gray, violet looks blue, brown looks tan, etc.  On some I had no clue. (At least for me and my feeble eyes!)

I finally found the problem. It was the ignition switch. The part of the switch going to the accessories part of the fuse block apparently was internally "fried". It is sure nice to have brake lights again.