94 trans not locking up

I’ve done searches but not coming up with anything.

94 2500 213k 6.5td. It will lock up once when initially started but if I stop at a stop sign and go it will not again until I shut it off. I am getting a brake on code. Which I’m sure is why it’s not locking but I can’t figure out why. Switch is new, and it doesn’t look like there’s any sort of adjustment on these. Not sure which way to go. I can’t drive it like this, don’t wanna cook the trans. Any ideas?

Hi

What is the code you are getting ??? What number ???

Sorry for the delay, I haven’t had time to toss the code reader on. It’s a code 37

I also had a similar weird problem like yours and it was the 3rd brake light. May be totally different than your issue. I had a wire that burned at the 3rd light housing, and was grounding, causing my trans to act stupid.. Good luck!

#37 is "Brake switch stuck on"