On that year model it appears the brake switch (cruise side) is a closed loop between the cruise module, cruise switch, and that half of the brake switch.
It appears that 7747 got the 12v brake switch signal for TCC unlock at pin a12 (purple wire) from a "diode module" that received the 12v from a switch on the RWAL from "gauge/idle" fuse.
Confusing as hell, hope that helps. Those old diagrams can be tough to follow the flow.
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