Which plug on the ecm do you check the crank position voltage at? The ecm is in the passenger kick panel correct?

I also checked codes, it had a p1884?

 

1884 is actually a fault code for 8 different issues and will go away on it's own when your issue is resolved.
What is your truck doing wrong, do you have a scanner that can give you real time readings, if so that is the easiest way to verify a problem.