The quickest way to find out what that Orange Wire needs, is to turn on ASC - does the light come on?
No light? Look for the 8 volts from the receive - Probe for voltage, find the variable power (wiper arm) and the low side of the Squelch control pot - note the color code and trace the SQ power wires color codes back to their spots on the board. One spot for ground, one spot close to a transistor that is by the audio chip - then the one that more than likely is very close to where that Orange Wire goes - because of the required power routing for ASC to work.
Does the squelch work normally? It uses +8 volts from the RX line that powers the receive IF strip, it is switched - it also taps from the VR that trims the SQUELCH control - so there are two wires that arrive to the board from around that SQ VR trim pot. So if SQ works, but Auto part don't - then the wire that "fell off" is close to that area.
Why check for SQ to work? It isolates the wires location - for if SQ power wire from that area fell off, then the radio would go "Dead" because the comparator that triggers Mute from the squelch knob up front- would have no power to compare to - hence the "on break" Mute signal.
:+> Andy <+: