This is known as the "K6" relay in the Ford service manual. The function of this relay is to open the circuit between the two instrument panel turn indicator lamps during normal turn signal operation. During emergency flasher operation, the relay points are closed (normal position) and the two instrument panel indicator lamps flash at the same time.
Ford Part # C7WY-10B926-B.*NOTE*
Need help diagnosing a Cougar turn signal problem? Victor Yarberry is the world’s most knowledgeable expert on the subject. Vic has owned Cougars since the 1970's and is the designer of all of our solid state sequential systems. There is no question he cannot answer! Here is a link
to a great source of information on the subject.