[1966conv]

I do not know about your setup, but on the 66 the resistor wire runs from inside the distributor to the coil.
Do you have a shop manual or wiring diagram?

1966 Red Conv (200)
1966 White Pony Int.(289)A Code
1966 Coupe (289) C Code
MCA 36048

 

[Midlife]

I think you are describing the ground wire: distributor to coil. The resistor wire runs from the dashboard side of the firewall just short of the keyed ignition switch. It is the infamous pink wire, typically 0.3 or 0.6 ohms resistance.

http://clubs.hemmings.com/baymustang/flamicon.jpgLet me check your shorts! My multimeter is just a-waiting! Formerly known as Midlife in the old VMF.
King of the Old Farts *struts*

 

[Scott302]

The resistor wire 12250 is a thick gauge Pink wire that plugs into a Red/green wire out the back of the ignition switch. It plugs again into a red/green wire at the firewall. It acts as a ballast resistor to the coil. In '69's I think it also affects the tachometer

Scott
National Parts Depot
1965 Conv:Street driven concours
1966 Coupe: Daily driver and toy