Hello  Alex. yes communication has been lost with the ecm/pcm.  this does not mean you have a bad pcm,there could also be a network issue caused by another module in the same network. like the fcm=front control mude(under hood fuse box) ABS,SCM= steering control module, fcm=final control module if equipped, and shift level assembly if equipped. being that you only have one code the U0100 I am inclined to believe your issue is directly related to your pcm or (tcm )if your vehicle has a 3.7 L eng. however  I will do an auto scan  to make sure all other modules mentioned previously will show on the network. if one of this modules don't show up on the auto scan then suspect that particular module to be cause. a known module to cause this issue is mostly the abs but I have found fcm  and scm also. if all modules show up on the auto scan then yes suspect the pcm but before replacing it make sure to check powers and grounds to it.   the other big issue with Chrysler that you don't find in repair manuals or just about anywhere is the 5volt reference signal causing all kind of communication issues driving everyone nuts and replacing good modules and yes trowing communication code along with a bus error message on the ipc. the most famous one is the crank sensor but also cam and the tranny pressure sensor, any 5 volt sensor could do it. so in other words if your left only with the pcm being the cause of your issue and you checked power and grounds spend 10 more minutes and unplug all your 5 volt sensors. this is not likely but in 32 years I have seen all kinds of sh**t. good luck buddy letme know how it went.