Before I brought my car in for interior lighting to be installed, my navigation used to function this way:

Example:
Speed limit display on navigation: 55. The moment I hit 56 mph, I would hear a "Beep" to indicate that I have gone over the speed limit.

After interior lighting was installed, the "beep" disappeared. I have double checked the options and it says that audio warnings are turned on. I've even done a factory reset.

I returned the car to the dealer and they were unable to fix it. They say that you have to be going "very fast" for the audio warnings to go off. This is not true. 1 mph over the indicated speed limit will make it go off.

Anybody have any suggestions? The dealer or the manual have not been of any help. I don't know how this could have happened simply after having interior lighting installed.