In my 76 280c 114073 chassis. P.ower antenna wires are disconnected near the f 20 fusebox smaller pre fuse behind main fuse box . theres another red /blk wire coming fr main fuse box connected to the f20 . in wiring diagram it says f20 box is for aux fan . then on batt buss chart in diagram says red blk wire goes from f1 to f20 . question is is this a trigger wire ?? trying to relace f20 fusebox whats correct way to connect these wires ? since diagram doesn't cover trigger wire in manual