99 Grand Caravan p0403

I've already searched and found very ambiguous information regarding this code. I don't like throwing parts at cars but I can't seem to find the proper diagnostic procedure to troubleshoot the EGR control circuit. When I put my meter across the plug I get system voltage with key on and engine running. When I switch the scan tool to 'flow' under the EGR system test, nothing changes. The voltage stays the same and the engine idle doesn't change. Is system voltage supposed to be there at this time? What is supposed to happen when the ECM commands the EGR to open?

T-shooting is under "Possible Solutions". http://www.obd-codes.com/p0403

Cool. Thanks!