My guess is that your headlight switch is mushy and not getting current to headlight motors. I had this happen all last weekend, and found that the switch could be manipulated on occasion to open the lights. I'm ordering a new switch.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.