Engine/Transmission (1998.5 - 2002) Transmission line pressure check

[Challenger-II]

I tried to check my transmission's line pressure at idle yesterday but could not get a reading? Should this be checked while in gear or is in park ok? Don't trust the wife stepping on the brake while in gear and me under the truck... ... . life insurance policy! Maybe my gauge is bad? I hooked up to the accumulator port as per the service manual so I know that is not the problem.

 

[fox]

It must be in drive.