I think an in depth wiring check and use of a meter to check voltage and poss current is needed.
I know of an Avenger where dip switch burnt out but that was where a previous owner fitted 2 x 100 watt bulbs but no relay and resultant 18 amps was too much for switch contacts which overheated and melted plastic parts of switch , its a wonder that wires survived!
Is it possible a problem occured when alternator was wired or possibly a main earth disturbed.So check the wiring using the meter and ensure alternator cable is suitable for at least 1 1/2 times alternators rated max output.Check alternator mount to clean metal on engine and if new unit has a separate earth terminal this has been wired up.
A missing earth will mean wiring will try to find a substitute track to earth and that can be via any number of other circuits, even via metal control cables