Window Motor Circuit from
http://www.fordfuelinjection.com/
Note that the internal circuitry for the master switch is specific to '78-86 Broncos, and the most-common base color for the wires between the switches is PURPLE; not pink (the base color for door lock circuits).
See also:
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Normal operation is as follows:
RAISE from the dash switch:
Power flows thru fuse 14 thru the LB/BK wire thru the IP switch UP contacts thru the P/LG wire thru the key switch UP contacts thru the Y/R wire to the motor; then it grounds thru the motor's internal CB, out thru the R/Y wire thru the latch switch thru the T/Bk wire thru the key switch DOWN contacts thru the Pk/LB wire thru the IP switch DOWN contacts to the Bk wire to the ground in the kick panel (or dash on older Broncos).
LOWER from the dash switch:
Power flows thru fuse 14 thru the LB/BK wire thru the IP switch DOWN contacts thru the Pk/LB wire thru the key switch DOWN contacts thru the T/Bk wire thru the latch switch thru the R/Y wire thru the motor's internal CB to the motor; then it grounds out thru the Y/R wire thru the key switch UP contacts thru the P/LG wire thru the IP switch UP contacts to the Bk wire to the ground in the kick panel (or dash on older Broncos).
RAISE from the key switch:
Power flows thru fuse 12 thru the BK/Wh wire thru the key switch thru the UP contacts thru the Y/R wire to the motor; then it grounds thru the motor's internal CB out thru the R/Y wire thru the latch switch thru the T/Bk wire thru the key switch DOWN contacts thru the Pk/LB wire thru the IP switch DOWN contacts to the Bk wire to the ground in the kick panel (or dash on older Broncos).
LOWER from the key switch:
Power flows thru fuse 12 thru the BK/Wh wire thru the key switch DOWN contacts thru the T/Bk wire thru the latch switch thru the R/Y wire thru the motor's internal CB to the motor; then it grounds out thru the Y/R wire thru the key switch UP contacts thru the P/LG wire thru the IP switch UP contacts to the Bk wire to the ground in the kick panel (or dash on older Broncos).
Note that in ALL cases, EVERY switch is used, and the circuit ALWAYS grounds at the same point.
To add a simple self-diagnostic capability, wire a 12V lamp across the latch safety switch terminals, and mount it in the tailgate shell above the lock cylinder in the inside sill (through a carpet retainer hole if present). If either control switch is activated, and the only thing preventing the glass from moving is the safety switch, the lamp will light and be visible to a person using either switch.
