2000 Dodge Intrepid ECM/PCM

First of all, are these two terms different or are they the same when talking about replacing it/them. I am asking this question because in my repair manual I do not see anything that says ECM -- but, refers to only the PCM. At the auto store they refer to it as the PCM.

Secondly, my engine light is on due to the following OEM number (P0601) and the following is a list of probable causes. According to a printout given to me by auto store.

1. - Shorted input sensor
2. - Shorted electrical circuit
3. - Failed ECM

On that note, I want to go in order when troubleshooting and hopefully not have to get the $450.00 ECM replaced. Where is the input sensor and how do I check to see if it is shorted/electrical circuit?