If you have replaced your sequential unit in the trunk with one of our new solid state sequential units and are still having problems then the turn signal switch is most likely the culprit as the only other part to the system is the wiring harness itself. The relay under the dash is almost always weak (pulsates dimly instead of distinct blinking) but its sole purpose is to illuminate the directional arrows on the dash and does not affect the operation of the tail lights. Often when your brake lights are not working the turn signal switch is the culprit as the brake lights feed through the turn signal switch.Replaces Ford part # C7ZZ-13341-E. *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. Here is great diagram that may help as well.