Tylenol pm causes constipation?

Yes, it is the "PM" component, diphenhydramine, that is mostly responsible. It will also hinder the ability to urinate.

Yes acetaminophen (Tylenol) definitely does, so can Ibuprofen (Motrin, Advil), Aleve and especially prescription pain meds.

I had never heard of this before. Your question sent me Googling. Here's what I found . . .

Tylenol pm side effects: Dizziness, drowsiness, constipation, stomach upset, 
blurred vision, or dry mouth/nose/throat may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

There are more, Google it and see the list.