I just got another mustang. It's a 1998 v6 convertible. The problem that I am having is when you press on the lock and unlock button it eathier does nothing or just does one of the 2. When I was in it this morning, with the car off I pressed the button and every light in the car would light up(Aka backlighting on all of the electronics) Does anyone have any ideas?

 

I'd say check your underdash fuses.