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Yes, one yellow wire comes from the 50amp fuse(#11) and splits into 4 yellow wires at the ignition switch
Yes, with ignition switched in START position, its sends 12v out to fuse #24 on a red/blue wire
The key cylinder uses a gear and pulls and pushes the Actuator rod inside the steering column to slide the ignition switch into its 4 positions, ACC, OFF, RUN, START
Can you test the ignition switch manually?
You could have a problem with Actuator Rod not moving ignition switch all the way to START position
That same red/blue wire also sends power to fuse #28 which should MUTE the radio for startup