Saturn 2000 PO446 EVAP Code: Pressure Too High Despite Replaced Vent Solenoid and TPS

I have a 2000 Saturn with a persistent PO446 EVAP system code. I've already replaced the vent solenoid and tested with a known good throttle position sensor (TPS). When the sensor is disconnected, the vehicle still reports excessive evaporative pressure, preventing the EVAP service bay test from completing. Using a Multimeter (Modis), I read 2.9 volts with a pressure reading of 6.75 psi when the sensor is unplugged. The fuel tank has been removed and inspected. Given these symptoms, I suspect either a wiring short or an issue with the Vehicle Control Module (VCM). Any insight into possible causes or diagnostic steps would be greatly appreciated. Thanks, Kickstand.