Where is the brake lamp failure sensor located? on 2003 Toyota Highlander

all my brake lights do not work. all running lights work except when i step on the brake, the brake lights do not go brighter.

Asked by for the 2003 Toyota Highlander
check bulb ,fuse,/ relays underhood and under the dash,I always say do the visual checks first they cost you nothing. check for corrosion on bulb socket (actually take the bulb out of the socket and closely inspect for corrosion) check wires and all connections related to the brake light circuit. I hope you havent had this problem for long this needs immediate attention, If corrosion or a leakage is happening due to moisture getting inside the lense cover also have that rubber area replaced,. If these checks dont work then you can move to questioning the brake light switch operation.