Key will not turn completely off

The key will not turn off completely and I am unable to pull the key out of the ignition leaving the radio etc, on due to the solenoid valve not de-energizing. I have to disable the battery so the solenoid will allow me to turn the key off completely and then I am able to pull it out. It seems that the solenoid is a safety of some sort either tied to the position of the console shifter to ensure it is in the park position or something. I am just wondering where the 12VDC volts is being fed from so I can locate the problem.