When I had my Tahoe tuned, I wish I could remember when they set it to lock up. I know just cruising it locks up early 40/45 and when I'm on the highway it locks up later. He also did something around 50mph to make it seem like I have another gear, wish I could remember but, it's been so long. Finding someone reputable in my area has not been easy so, I let it be for now.
I will replace the brake light switch for preventative measures though. I know years ago it randomly went on me. Noticed my cruise didn't work.
Appreciate the info