That column wiring is a mess.
Bust out the volt/ohm meter and start checking voltage and continuity with the switch in the different positions.
'74-'77 Column Connections
Blue=12v from turn flasher to turn switch, circuit #44
white-blue=right front turn and indicator lamp, circuit #2
green=right rear brake and turn lamp, circuit #282
green-white=left front turn and indicator lamp, circuit #3
yellow-black=left rear brake and turn lamp, circuit #283
red-black=12v brake switch to turn signal switch, circuit #810
blue-yellow=12v horn relay to horn switch, circuit #1
white-red=12v from hazard flasher to hazard switch, circuit #385
blue-red=12v from headlight switch to PRNDL light, #19