Hi! It sounds like the same problem I had a few months back. My exterior failure lamp came on, and I couldn't find a bad bulb ANYWHERE! One day I was in front of a diesel truck at a red light and I could see the rear of my car in his enormous front bumper. I saw that my brake lights were remaining on when I removed my foot from the pedal. Check and see if your brake lights remain on when the brake pedal is NOT pushed. (I dont know if it needs to be in gear or not) Anyway, I took my Baby Blue to the Chrysler dealership, and had to have a part replaced (sorry, I cant recall the part name), it was rather costly - $1,100, and took nearly a week to get. The service mgr said it was some kind of computer part for the lights?
Hope this helps!
June