PCM burn out the Vent Solenoid

I have replaced several of these Vent Solenoids on Saturn and other GM cars. There is a red wire from a 10 amp fuse that goes to the solenoid and the Engine Computer uses a white wire to ground the solenoid. Have the dealership unplug the Solenoid and test each wire individually. I don't see how the Computer could suddenly be providing 12 volts to the solenoid, from a part of the Computer that operates as a grounding function. Make them show you that there is 12 volts from the white wire, and I mean in person, with the solenoid unplugged and with the key on engine off. If they complain , take your car to a another shop and have them ONLY replace the Vent Solenoid and clear the code. I do Emissions work in N CA was a GM Dealership Journeyman Diagnostician, and I have replaced about 50 of these Vent Solenoids and I have yet to see this problem, so I am NOT convinced, not until I SEE the 12 volts from the white wire.