1991 Cougar Headlight Problem

Hi,
My son's car is a 1991 Mercury Cougar. While driving his headlights will just go off. We tested the battery and alternator, can't find an unconnected wire. Can anyone suggest another lace to look? Any help appreciated.
Thanks in advance

Check to see if it's shorting out anywhere and check for any moisture in the headlight harness.

If you don't find anything then check ask on the Tech Forum on http://www.tccoa.com I'm sure you'll get help there.

Seabass

Thank You