If your Nissan's ignition switch is failing, there are two classic signs that it needs replacement: the lock cylinder will not turn to the "On" position or the ignition key will rotate in the lock cylinder but it cannot be removed. If your key is stuck in the ignition switch, tap the end of the key lightly with a hammer. Techniques for replacing the ignition switch can vary depending on the year and model of your Nissan, but there are some common steps.
Disconnect the negative cable from your Nissan's battery. If your Nissan is equipped with an airbag, disconnect the electrical connection leading to your airbag so that it will not inflate while you are working on your steering column. Look for a small panel on the bottom of your steering wheel where the airbag electrical connection is located. Wait 10 minutes for any built-up charges to dissipate before continuing.
Use a screwdriver to remove the steering column covers and panels from your Nissan. Use a screwdriver or socket wrench set to remove the knee bolster and other coverings from underneath the driver's-side dashboard. Keep all screws and connectors for each of the panels with the panels.
Disconnect the electrical connections to your ignition switch. There will be one or two, depending on your year and model. One of the connections is always located directly on the outside assembly of the ignition switch. The other connection, if you have one, will be located behind the knee bolster. Maxima models between 1993 and 2004, for example, have this second connection. If in doubt, disconnect all electrical connections that you see on the underside of your dashboard and steering column.
Unscrew the mounting screws or bolts for your ignition switch. Some models use a removable lock cylinder, which has a pinhole that needs to be depressed before sliding out the lock cylinder from the ignition switch. If you have this ignition switch design, you also need to rotate the key to the accessories position. However, other models require the removal of the entire ignition switch assembly. Look at the top of the ignition switch housing for the mounting bolt holes. Some models, such as Maxima, use snap-off bolt heads as a security measure against auto theft. Use a power drill and screw extractor to remove the snap-off bolts from the mounting assembly of the ignition switch.
Install the new ignition switch assembly. Use a socket wrench to rotate the bolt heads until they snap off by themselves. Reconnect all of the electrical connections and the negative battery cable. Try your new ignition switch using the new key for your lock cylinder. If the Nissan turns on, then you have installed the ignition switch correctly.
Reinstall the panels, covering and knee bolster to the underside of the dashboard. Reconnect the steering column covers last. Reconnect the electrical connection leading to your airbag.