2004 headlights on/off wire signal

May 30, 2022
Thunderbird Year
Guessing it’s one of the wires on the FEM.

Needed for aftermarket Kenwood headunit to enable dimming the screen at night.

Illumination wire in factory harness appears to be variable based on illumination dial. I need 12V/0V for the Kenwood.

If it’s another pin on the factory harness, that would be ideal!

Thanks in advance.
Feb 9, 2019
Thunderbird Year
Hmm....that thumbwheel on the dash sends a signal (a pulse-width modulated signal IIRC) to the FEM and that computer processes the signa thenl forwards the dimming signal to the lights. Its not straight forward (I don't have the schematics in front of me so I'm going from memory).