brake lights not working when in gear 2002 Explorer

just discovered yesterday that the brake lights on my wifes '02 explorer are not working.
they work if she is sitting in park.
once in gear and driving neither of the 3 brake lights work.

anyone know what is causing this?

fuse is fine.

i'm thinking it must be something with the brake pedal or the multifunction manual gear arm. note- also have to push in extra hard on the brake pedal to even get the gear arm to switch out of park.

much appreciate any help.

Sounds like you need to take a look at the brake switch. Since it controlls all the brake lights and the shift lock solenoid (what makes the clicking noise when you press on the brake to move the shift lever out of park). You should be able to see whats going on with a simple test light. There should be power in all the time and power out only when you step on the brake pedal.