electronic malfuntion?

today i was driving my 2003 4.6, when i used the horn, the traction, ABS, and BRAKE lights came on and went off... it was wierd, so i did it again and same thing.. every time i honk those lights turn on and off, untill the speedometer went up and down and back to its orginal point, then the service engine light came on.. EVERY time i honk it happens. any ideas?

PS: today was the first time it snowed in LA and my car was under it for 12 hours untill i started it.