The Powertrain Control Module (PCM) on a 2001 Dodge Ram diesel pickup is located
under the hood, typically on the driver's side fender apron. However, the exact location can vary slightly depending on the specific engine and options. It's usually a fairly large, rectangular black box. You may need to remove some shrouds or access panels to see it clearly.
It's best to consult a repair manual specific to your 2001 Dodge Ram diesel model (which engine you have is crucial - a Cummins, etc.) for the precise location. A diagram showing the PCM's location would be in the manual.
