afternoon all,

recently purchased a "project" mustang that the previous owner didn't treat to kindly and am in the process of restoring it/repairing it. in their infinite wisdom they decided to cut the pigtail off of the wiring harness for the radiator fan; I have a new motorcraft pigtail, however the wires are not labeled.

what would you suggest to reference for finding which wire is pos, and which is neg on the pigtail?

 

From being under the hood today, I remember the bottom post is pos. My project cars last owner put in a bypass switch and bottom wire is connected direct to battery.

 

To answer your initial question, with the connector unplugged, Key ON, Engine Off, whichever pin in the plug has 12 volts is the power wire. Which ever one doesn’t, is the ground wire. Good luck...