Parking brake and speed sensor

Hi there, I recently purchased a 1996 peterbilt 377.
I’m wondering why when you push in the parking brake , it doesn’t release until you hold the service brake all the way down for about 3 seconds. Is this normal or is there something I should look for That is wrong.

I also got the check engine light with a code 241. I recently changed the speed sensor and the harness but it still has the Check engine light . After I changed it my accelerator would accelerate all the way without being touched but haven’t had that happen again. What should I do?

thanks