hey i need some quick help, im trying to find a wiring diagram for the headlight switch of an 03 mustang on here and this search is not providing anything of me, i need to know which wire goes to the dash to dim and brighten the back light... im trying to wire some after market gauges and this gray wire is not doing anything for me... need help

 

The best place is usually to tap the light for the hvac cluster. Or, if you have a test light, pull the switch and find one that way. Not to difficult.

 

+1

 

It's the light blue wire with the red stripe.