Timing chain issue... When the chains and or cams move it affects vacum. Which create the brake pedal issue. Working on a 2000 LS 3.9L right now with same issue
brake switch located on the top of the brake pedal
If you mean that you can't shift the shifter while pressing on the brake, I would say that it is down by the brake pedal.
It would be the rubber pad that sits on your brake pedal. Unless they were referring to brake pads, which are the pads which enables your vehicle to stop by pressing the brake pedal.
Usually that would be caused by a faulty brake light switch connected TO the brake pedal. If the brakes work the pedal is probably ok.
Check the switch adjustment on the brake pedal arm.
It should be on either the pedal shaft or the pedal frame.
out of brake fluid?
if brake pedal is soft , either there is air in the system ,a brake fluid leak, or brake linings and pads are worn allowing the pedal to travel to far if there is a fluid leak, this can usually be found by getting under vehicle and looking at inside of wheels for brake fluid
A dashboard light appearing when brake pedal is depressed usually means brake fluid is low.
And why in the world would you want to do that, as the rear brakes which are operated by the parking brake are already activated by the brake pedal. Do not even think of doing this.
Start the engine and then push the brake pedal down. If it is soft and easy to push then the booster is okay. If booster is BAD the brake pedal would be hard to push.
If none of the brake lights are working i would suspect the brake switch at the brake pedal.