How do you know if the starter needs to be replaced on a 1993 Nissan Altima?

Take the steering column housing off (usually held by 4 screws from the bottom) and remove the starter cap from the back of the ignition cylinder. In a Nissan, the ignition cylinder usually has a T shaped pin which turns the starter. if you can start your vehicle by turning the starter cap with a screw driver, you probably don't have an issue with the starter.