The ignition tumbler inside the Nissan Quest minivan is secured to the steering column with a retaining clip. The tumblers are small pins inside the cylinder lock that act like a puzzle. When you insert the key into the ignition, there are ridges on the key that push up (or down, or both up and down, depending on the key and ignition lock) to line up the pins, solve the "puzzle" and allow you to unlock the ignition so you can start the vehicle. When these pins jam, seize or break, you must remove them along with the ignition cylinder.
Remove the two side screws on each side of the Quest's steering column cover, using the screwdriver.
Remove the screws on the underside of the steering column cover, and pull the bottom half of the cover down to remove it.
Place the pin punch into the small hole underneath the ignition lock.
Apply upward pressure on the pin, and pull the ignition lock out of the steering column. If you can get the ignition key into the ignition and turn the key to the "II" position, this might make the job of pulling the lock out of the steering column a little easier.
