electrical problem

I have a 1978 Ford Thunderbird and every time I turn on the exterior lights I hear a click from under the dashboard,and both the dash lights and taillights go out.A couple of seconds later theres another click and the lights come back on.

Might I direct you to the proper forum. You'll find your answers to your question here.

http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=957

It sounds like a circuit breaker is tripping and then resetting after a few seconds. Lay on the drivers side floor and while someone turns on the lights see if you can determine where the clicking sound is coming from (the fuse panel or the light switch). I didn't think that year came with resettable circuit breakers. The fuse panel should be up under the dash near the steering column. Look for the location of the fuse for the instrument panel/tail lamps. If it is a circuit breaker it should be a little silver can sticking out of the fuse panel. Try replacing it and be sure to use the correct amp rated type. If it calls for a 15 amp don't put in a 20 amp!