Classic/Antique Car Repair: 67 cougar light problem, 67 cougar, auto electrician

Question
hope you can help.i have a 67 cougar 289 2v.119,000 miles.when i apply my brakes all interior lights and head lights dim with engine off.with engine on at a stop all lights dim slightly and dash lights cut on and off.while driving and begin to brake there is slight dimming.no problem if brakes not applied.i had the alternator and battery checked at a local shop and they thought the problem was the voltage regulater.they put a new one on and it made no differance.thanks for any help you can provide.i hate to start replacing everything.this car was very well maintained by the previous original owner.i bought the car 4 months ago and have put 400 miles on it.

Answer
Your brake lights are drawing excessive current, probably due to a problem with the sequential tail light controller.  

This is going to take a pretty skilled auto-electrician to track down, and definitely someone who is familiar with the 67 Cougar sequential tail light system - which narrows down the choice of a possible helper to a VERY FEW! That system was complex and understood by very few folks - and most have been disabled by now.  

If you have the shop manual for the car, consult the wiring diagram to see which wire you can disconnect to disable the sequential brake lights - perhaps this will make the problem go away.   I know that there are vendors selling a modern transistorized equivalent control circuit which you might find the best way to get past this problem.

I'm sorry that I don't know of any other way to cure this.  You have a rare car with a VERY rare feature - there were only a few cars that used this system that I know of - a few T'birds of the late 60s, and the 69 Imperial are the only ones I can think of off hand.

See if you can find someone on the club web-sites for your or those other cars who offers repair and diagnosis of that system.  I'm afraid this was one of Ford's "better ideas" that didn't work out so well.

Dick