To install a brake light switch in a vehicle, remove the cover behind the brake pedal, remove the old switch, and install the new unit. Tools required for the process included a regular and metric-size socket set and a Phillips screwdriver. A flashlight may be useful to help you see behind the brake pedal.
Open the driver's side door, and get down on your knees so that you can see behind the brake pedal and locate the cover plate for the switch. Typically, the plate is fastened on by a number of Phillips-head screws that may vary between different vehicle models. It is also possible that the plate may be connected by 10-millimeter bolts. Remove the screws or bolts holding the plate on, and then set them and the plate to the side.
The brake switch is under the plate that was removed. Disconnect the electrical connector, and remove the screws holding the switch in place. Screw the new connector in place, plug in the electrical connector, and then reattach the plate.
Before purchasing a replacement, examine the existing brake switch. It is possible that it has moved out of alignment and is still functioning properly, but needs to be realigned. It is also possible that the switch is stuck on or off and can be repaired.