How do you lock a dodge sprinter van while engine is running?

You can't lock a Dodge Sprinter van from the outside while the engine is running. The system is designed to prevent this to avoid someone trapping themselves inside or stealing the vehicle. The key needs to be in the ignition for the engine to run, and the locking mechanism is usually tied to the ignition system. Trying to lock it from the outside will either not work or will automatically unlock it.