Headlight short

Its sort of typical for the novice to assume a black wire casing means ground wire. No so. Black is on the ground side of the circuit but where the current actually reaches chassis ground is on other side of whatever the black wire is feeding. Consider the amp gauge. One red wire is initial feed. Black wire it the side where current is off to seek a ground somewhere.
Melting of this harness connector is somewhat common, especially in Jeeps where those owners have added more lights to the circuit.
A new connector is listed online for Jeep CJ. Same connector for your mopar.