I see that it references barometer on page 10, but doesn't explain if there is a separate sensor or whether or not it is picked up from the MAP. The older cars had a 3 way solenoid that would toggle the pressure source from the manifold source to atmospheric at times to get a sample. Being as the map sensor is directly mounted to the throttle body on a Magnum engine, that would not be the case here. So unless there is a separate sensor somewhere (which I can't find listed as a replacement part) I have to assume that sample comes from the MAP sensor during cranking.