I have a '99 Voyager and the interior lights won't activate when opening the driver or passenger doors. They will come on when using the sliding doors and rear hatch. It's kind of irritating when entering the vehicle alone at night and not being able to see what you're doing until the lights are turned on.

BTW, i've already checked the dimmer switch.

sounds to me like its one of the door switches. i will check mine tomorow to see exactly where they are but try to find and clean off the door contacts. you can sand them off very lightly with some sand paper if there is corrosion on them.

hope that helps