Finishing up resto on '69 442, getting ready to install interior, I have the front to rear harness installed, (taillights etc), this car came with a factory option rear defroster, Purple 14ga wire loose to the rear as well, but I have an unidentified wire that comes out of the same connector as the defroster wire, runs about 5' and loops back to the connector under the dash. I can't find it on my wiring schematic. It is actually a black 14ga wire with white fabric insulation. Please help identify purpose and install path, thanks, Greg also see pic

 

That might be the resistor wire for low speed on your rear defroster.

 

Yellowstatue is correct.

 

Sounds right to me, too.

- Eric