All cars rely on a lock cylinder that works with the ignition switch to fire the engine. If there is any problem with the cylinder itself, you need to replace the cylinder to repair the ignition system. The removal and installation process of a Corolla's ignition cylinder can vary; some models have added features like an engine immobiliser system. This can depend on the year your car was made. Replacing the cylinder will mean you must change keys also.
Disconnect the Corolla's negative battery cable: Loosen the black cable's clamp nut with a wrench to separate the clamp from the negative terminal.
Remove the trim covers from the steering column; the cover is in two pieces, with the screws on the underside of the lower cover. Skip to Step 5 if the Corolla doesn't have an engine immobiliser system.
Pry off the plastic shroud around the ignition cylinder gently and disconnect the electrical connector. Lift up the shroud's edge off the locating tab just enough to slip it off the cylinder.
Pry the illumination ring lightly off he front end of the cylinder and then remove the unlock arming switch for the immobiliser system.
Turn the ignition switch to the "accessory" position.
Insert a small screwdriver or punch into the hole within the cylinder housing, then pull out the cylinder with the key inside it.
Press on the retaining pin on the replacement cylinder, insert the key into the cylinder and insert the cylinder into the housing until its pin engages with the locating hole.
Turn the cylinder and switch back to the lock position.
Reconnect the arming switch, illumination ring and electrical connector/shroud for the immobiliser system if needed.
Reconnect the steering column covers with their screws and your screwdriver.
Reconnect the negative battery cable.