brake light switch wiring

how does everyone wire there brake light switch wires for the 5.3l computer.
its one of the things im stuck on i see alot of build where they are buying a new brake light switch out of like a Monte carlo most of these projects are older vehicles though so its throwing me off

99 tahoe 4x4 stock gauges
01 5.3l with the 4l60e and np246 witch painless wiring harness

I was told to just wire it into the old signal from the old harness.

What im trying to figure out is on the the wiring diagram I have it shows the signal as a purple wire. On my new harness I have 2 wires saying it's for the brake light switch a purple and a pink wire

You are using an aftermarket powertrain wire harness in a 99 Tahoe? Why?

My guess is that the pink wire from the Painless harness is a feed circuit. Since your vehicle already has a factory brake switch and feed circuit, the pink wire will be unused.

Maybe this will help

http://imgur.com/O59mIml

http://i.imgur.com/O59mIml.png